Table of contents

    08 December 2022, Volume 32 Issue 1 Previous issue    Next issue
    TOPICAL REVIEW—Physics in micro-LED and quantum dots devices
    Bottom-up approaches to microLEDs emitting red, green and blue light based on GaN nanowires and relaxed InGaN platelets
    Zhaoxia Bi(毕朝霞), Anders Gustafsson, and Lars Samuelson
    Chin. Phys. B, 2023, 32 (1):  018103.  DOI: 10.1088/1674-1056/aca9c2
    Abstract ( 312 )   HTML ( 10 )   PDF (3311KB) ( 250 )  
    Miniaturization of light-emitting diodes (LEDs) with sizes down to a few micrometers has become a hot topic in both academia and industry due to their attractive applications on self-emissive displays for high-definition televisions, augmented/mixed realities and head-up displays, and also on optogenetics, high-speed light communication, etc. The conventional top-down technology uses dry etching to define the LED size, leading to damage to the LED side walls. Since sizes of microLEDs approach the carrier diffusion length, the damaged side walls play an important role, reducing microLED performance significantly from that of large area LEDs. In this paper, we review our efforts on realization of microLEDs by direct bottom-up growth, based on selective area metal-organic vapor phase epitaxy. The individual LEDs based on either GaN nanowires or InGaN platelets are smaller than 1 μ in our approach. Such nano-LEDs can be used as building blocks in arrays to assemble microLEDs with different sizes, avoiding the side wall damage by dry etching encountered for the top-down approach. The technology of InGaN platelets is especially interesting since InGaN quantum wells emitting red, green and blue light can be grown on such platelets with a low-level of strain by changing the indium content in the InGaN platelets. This technology is therefore very attractive for highly efficient microLEDs of three primary colors for displays.
    Ion migration in metal halide perovskite QLEDs and its inhibition
    Yuhui Dong(董宇辉), Danni Yan(严丹妮), Shuai Yang(杨帅), Naiwei Wei(魏乃炜),Yousheng Zou(邹友生), and Haibo Zeng(曾海波)
    Chin. Phys. B, 2023, 32 (1):  018507.  DOI: 10.1088/1674-1056/aca7e8
    Abstract ( 259 )   HTML ( 9 )   PDF (4922KB) ( 197 )  
    Benefiting from the excellent properties such as high photoluminescence quantum yield (PLQY), wide gamut range, and narrow emission linewidth, as well as low-temperature processability, metal halide perovskite quantum dots (QDs) have attracted wide attention from researchers. Despite tremendous progress has been made during the past several years, the commercialization of perovskite QDs-based LEDs (PeQLEDs) is still plagued by the instability. The ion migration in halide perovskites is recognized as the key factor causing the performance degradation of PeQLEDs. In this review, the elements species of ion migration, the effects of ion migration on device performance and stability, and effective strategies to hinder/mitigate ion migration in PeQLEDs are successively discussed. Finally, the forward insights on the future research are highlighted.
    Review of a direct epitaxial approach to achieving micro-LEDs
    Yuefei Cai(蔡月飞), Jie Bai(白洁), and Tao Wang(王涛)
    Chin. Phys. B, 2023, 32 (1):  018508.  DOI: 10.1088/1674-1056/ac90b5
    Abstract ( 350 )   HTML ( 10 )   PDF (3004KB) ( 357 )  
    There is a significantly increasing demand of developing augmented reality and virtual reality (AR and VR) devices, where micro-LEDs (μLEDs) with a dimension of ≤ 5 μ m are the key elements. Typically, μLEDs are fabricated by dry-etching technologies, unavoidably leading to a severe degradation in optical performance as a result of dry-etching induced damages. This becomes a particularly severe issue when the dimension of LEDs is ≤ 10 μ m. In order to address the fundamental challenge, the Sheffield team has proposed and then developed a direct epitaxial approach to achieving μLEDs, where the dry-etching technologies for the formation of μLED mesas are not needed anymore. This paper provides a review on this technology and then demonstrates a number of monolithically integrated devices on a single chip using this technology.
    SPECIAL TOPIC—Physics in micro-LED and quantum dots devices
    A polarization mismatched p-GaN/p-Al0.25Ga0.75N/p-GaN structure to improve the hole injection for GaN based micro-LED with secondary etched mesa
    Yidan Zhang(张一丹), Chunshuang Chu(楚春双), Sheng Hang(杭升), Yonghui Zhang(张勇辉),Quan Zheng(郑权), Qing Li(李青), Wengang Bi(毕文刚), and Zihui Zhang(张紫辉)
    Chin. Phys. B, 2023, 32 (1):  018509.  DOI: 10.1088/1674-1056/ac9b35
    Abstract ( 260 )   HTML ( 4 )   PDF (1210KB) ( 153 )  
    A low hole injection efficiency for InGaN/GaN micro-light-emitting diodes (μLEDs) has become one of the main bottlenecks affecting the improvement of the external quantum efficiency (EQE) and the optical power. In this work, we propose and fabricate a polarization mismatched p-GaN/p-Al$_{0.25}$Ga$_{0.75}$N/p-GaN structure for 445 nm GaN-based μLEDs with the size of $40 \times 40 $μm$^{2}$, which serves as the hole injection layer. The polarization-induced electric field in the p-GaN/p-Al$_{0.25}$Ga$_{0.75}$N/p-GaN structure provides holes with more energy and can facilitate the non-equilibrium holes to transport into the active region for radiative recombination. Meanwhile, a secondary etched mesa for μLEDs is also designed, which can effectively keep the holes apart from the defected region of the mesa sidewalls, and the surface nonradiative recombination can be suppressed. Therefore, the proposed μLED with the secondary etched mesa and the p-GaN/p-Al$_{0.25}$Ga$_{0.75}$N/p-GaN structure has the enhanced EQE and the improved optical power density when compared with the μLED without such designs.
    Concerted versus stepwise mechanisms of cyclic proton transfer: Experiments, simulations, and current challenges
    Yi-Han Cheng(程奕涵), Yu-Cheng Zhu(朱禹丞), Xin-Zheng Li(李新征), and Wei Fang(方为)
    Chin. Phys. B, 2023, 32 (1):  018201.  DOI: 10.1088/1674-1056/ac98a5
    Abstract ( 283 )   HTML ( 2 )   PDF (2809KB) ( 154 )  
    Proton transfer (PT) is a process of fundamental importance in hydrogen (H)-bonded systems. At cryogenic or moderate temperatures, pronounced quantum tunneling may happen due to the light mass of H. Single PT processes have been extensively studied. However, for PT involving multiple protons, our understanding remains in its infancy stage due to the complicated interplay between the high-dimensional nature of the process and the quantum nature of tunneling. Cyclic H-bonded systems are typical examples of this, where PT can happen separately via a "stepwise" mechanism or collectively via a "concerted" mechanism. In the first scenario, some protons hop first, typically resulting in metastable intermediate states (ISs) and the reaction pathway passes through multiple transition states. Whilst in the concerted mechanism, all protons move simultaneously, resulting in only one barrier along the path. Here, we review previous experimental and theoretical studies probing quantum tunneling in several representative systems for cyclic PT, with more focus on recent theoretical findings with path-integral based methods. For gas-phase porphyrin and porphycene, as well as porphycene on a metal surface, theoretical predictions are consistent with experimental observations, and enhance our understanding of the processes. Yet, discrepancies in the PT kinetic isotope effects between experiment and theory appear in two systems, most noticeably in water tetramer adsorbed on NaCl (001) surface, and also hinted in porphycene adsorbed on Ag (110) surface. In ice Ih, controversy surrounding concerted PT remains even between experiments. Despite of the recent progress in both theoretical methods and experimental techniques, multiple PT processes in cyclic H-bonded systems remain to be mysterious.
    Time-resolved K-shell x-ray spectra of nanosecond laser-produced titanium tracer in gold plasmas
    Zhencen He(何贞岑), Jiyan Zhang(张继彦), Jiamin Yang(杨家敏), Bing Yan(闫冰), and Zhimin Hu(胡智民)
    Chin. Phys. B, 2023, 32 (1):  015202.  DOI: 10.1088/1674-1056/ac8e95
    Abstract ( 263 )   HTML ( 3 )   PDF (1274KB) ( 89 )  
    A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The time-resolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By comparing the simulated spectra obtained by using the FLYCHK code with the measured titanium spectra, the temporal plasma states, i.e., the electron temperatures and densities, are deduced. To evaluate the feasibility of using the method for the characterization of Au plasma states, the deduced plasma states from the measured titanium spectra are compared with the Multi-1D hydrodynamic simulations of laser-produced Au plasmas. By comparing the measured and simulated results, an overall agreement for the electron temperatures is found, whereas there are deviations in the electron densities. The experiment-theory discrepancy may suggest that the plasma state could not be well reproduced by the Multi-1D hydrodynamic simulation, in which the radial gradient is not taken into account. Further investigations on the spectral characterization and hydrodynamic simulations of the plasma states are needed. All the measured and FLYCHK simulated spectra are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.57760/sciencedb.j00113.00032.
    LAMOST medium-resolution spectroscopic survey of binarity and exotic star (LAMOST-MRS-B): Observation strategy and target selection
    Jiao Li(李蛟), Jiang-Dan Li(李江丹), Yan-Jun Guo(郭彦君), Zhan-Wen Han(韩占文), Xue-Fei Chen(陈雪飞), Chao Liu(刘超), Hong-Wei Ge(葛宏伟), Deng-Kai Jiang(姜登凯), Li-Fang Li(李立芳), Bo Zhang(章博), Jia-Ming Liu(刘佳明), Hao Tian(田浩), Hao-Tong Zhang(张昊彤), Hai-Long Yuan(袁海龙), Wen-Yuan Cui(崔文元),Juan-Juan Ren(任娟娟), Jing-Hao Cai(蔡靖豪), and Jian-Rong Shi(施建荣)
    Chin. Phys. B, 2023, 32 (1):  019501.  DOI: 10.1088/1674-1056/ac9362
    Abstract ( 226 )   HTML ( 3 )   PDF (3317KB) ( 136 )  
    LAMOST-MRS-B is one of the sub-surveys of LAMOST medium-resolution ($R\sim7500$) spectroscopic survey. It aims at studying the statistical properties (e.g., binary fraction, orbital period distribution, mass ratio distribution) of binary stars and exotic stars. We intend to observe about 30000 stars ($10 {\rm mag}\leq G < 14.5$ mag) with at least 10 visits in five years. We first planned to observe 25 plates around the galactic plane in 2018. Then the plates were reduced to 12 in 2019 because of the limitation of observation. At the same time, two new plates located at the high galactic latitude were added to explore binary properties influenced by the different environments. In this survey project, we set the identified exotic and low-metallicity stars with the highest observation priorities. For the rest of the selected stars, we gave the higher priority to the relatively brighter stars in order to obtain high quality spectra as many as possible. Spectra of 49129 stars have been obtained in LAMOST-MRS-B field and released in DR8, of which 28828 and 3375 stars have been visited more than twice and ten times with $\rm SNR \geq 10$, respectively. Most of the sources are B-, A-, and F-type stars with $\rm -0.6< [Fe/H] < 0.4 $ dex. We also obtain 347 identified variable and exotic stars and about 250 stars with $\rm [Fe/H] <-1$ dex. We measure radial velocities (RVs) by using 892233 spectra of the stars. The uncertainties of RV achieve about $1$ ${\rm km \cdot s^{-1}}$and $10$ ${\rm km \cdot s^{-1}}$ for 95% of late- and early-type stars, respectively. The datasets presented in this paper are available at http://www.doi.org/10.57760/sciencedb.j00113.00035.
    Integrated, reliable laser system for an 87Rb cold atom fountain clock
    Zhen Zhang(张镇), Jing-Feng Xiang(项静峰), Bin Xu(徐斌), Pan Feng(冯盼), Guang-Wei Sun(孙广伟),Yi-Ming Meng(孟一鸣), Si-Min-Da Deng(邓思敏达), Wei Ren(任伟),Jin-Yin Wan(万金银), and De-Sheng Lü(吕德胜)
    Chin. Phys. B, 2023, 32 (1):  013202.  DOI: 10.1088/1674-1056/ac9e95
    Abstract ( 261 )   HTML ( 3 )   PDF (3177KB) ( 117 )  
    We designed, assembled, and tested a reliable laser system for 87Rb cold atom fountain clocks. The laser system is divided into four modules according to function, which are convenient for installing, adjusting, maintaining, and replacing of the modules. In each functional module, all optical components are fixed on a baseplate with glue and screws, ensuring the system's structural stability. Mechanical stability was verified in a 6.11g RMS randomvibration test, where the change in output power before and after vibration was less than 5%. Thermal stability was realized by optimizing of the structure and appropriate selection of component materials of the modules through thermal simulation. In the laser splitting and output module, the change in laser power was less than 20% for each fiber in thermal cycles from 5 ℃ to 43 ℃. Finally, the functionality of the laser system was verified for a rubidium fountain clock.
    Variational quantum simulation of thermal statistical states on a superconducting quantum processer Hot!
    Xue-Yi Guo(郭学仪), Shang-Shu Li(李尚书), Xiao Xiao(效骁), Zhong-Cheng Xiang(相忠诚), Zi-Yong Ge(葛自勇), He-Kang Li(李贺康), Peng-Tao Song(宋鹏涛), Yi Peng(彭益), Zhan Wang(王战), Kai Xu(许凯), Pan Zhang(张潘), Lei Wang(王磊), Dong-Ning Zheng(郑东宁), and Heng Fan(范桁)
    Chin. Phys. B, 2023, 32 (1):  010307.  DOI: 10.1088/1674-1056/aca7f3
    Abstract ( 587 )   HTML ( 11 )   PDF (3465KB) ( 612 )  
    Quantum computers promise to solve finite-temperature properties of quantum many-body systems, which is generally challenging for classical computers due to high computational complexities. Here, we report experimental preparations of Gibbs states and excited states of Heisenberg $XX$ and $XXZ$ models by using a 5-qubit programmable superconducting processor. In the experiments, we apply a hybrid quantum-classical algorithm to generate finite temperature states with classical probability models and variational quantum circuits. We reveal that the Hamiltonians can be fully diagonalized with optimized quantum circuits, which enable us to prepare excited states at arbitrary energy density. We demonstrate that the approach has a self-verifying feature and can estimate fundamental thermal observables with a small statistical error. Based on numerical results, we further show that the time complexity of our approach scales polynomially in the number of qubits, revealing its potential in solving large-scale problems.
    Fabrication of honeycomb AuTe monolayer with Dirac nodal line fermions Hot!
    Qin Wang(汪琴), Jie Zhang(张杰), Jierui Huang(黄杰瑞), Jinan Shi(时金安), Shuai Zhang(张帅), Hui Guo(郭辉), Li Huang(黄立), Hong Ding(丁洪), Wu Zhou(周武), Yan-Fang Zhang(张艳芳), Xiao Lin(林晓), Shixuan Du(杜世萱), and Hong-Jun Gao(高鸿钧)
    Chin. Phys. B, 2023, 32 (1):  016102.  DOI: 10.1088/1674-1056/aca14a
    Abstract ( 385 )   HTML ( 5 )   PDF (2193KB) ( 316 )  
    Two-dimensional honeycomb lattices show great potential in the realization of Dirac nodal line fermions (DNLFs). Here, we successfully synthesized a gold telluride (AuTe) monolayer by direct tellurizing an Au(111) substrate. Low energy electron diffraction measurements reveal that it is (2×2) AuTe layer stacked onto (3×3) Au(111) substrate. Moreover, scanning tunneling microscopy images show that the AuTe layer has a honeycomb structure. Scanning transmission electron microscopy reveals that it is a single-atom layer. In addition, first-principles calculations demonstrate that the honeycomb AuTe monolayer exhibits Dirac nodal line features protected by mirror symmetry, which is validated by angle-resolved photoemission spectra. Our results establish that monolayer AuTe can be a good candidate to investigate 2D DNLFs and provides opportunities to realize high-speed low-dissipation devices.
    Correlated states in alternating twisted bilayer-monolayer-monolayer graphene heterostructure Hot!
    Ruirui Niu(牛锐锐), Xiangyan Han(韩香岩), Zhuangzhuang Qu(曲壮壮), Zhiyu Wang(王知雨), Zhuoxian Li(李卓贤), Qianling Liu(刘倩伶), Chunrui Han(韩春蕊), and Jianming Lu(路建明)
    Chin. Phys. B, 2023, 32 (1):  017202.  DOI: 10.1088/1674-1056/ac9de4
    Abstract ( 347 )   HTML ( 6 )   PDF (5804KB) ( 252 )  
    Highly controlled electronic correlation in twisted graphene heterostructures has gained enormous research interests recently, encouraging exploration in a wide range of moiré superlattices beyond the celebrated twisted bilayer graphene. Here we characterize correlated states in an alternating twisted Bernal bilayer-monolayer-monolayer graphene of ~ 1.74°, and find that both van Hove singularities and multiple correlated states are asymmetrically tuned by displacement fields. In particular, when one electron per moiré unit cell is occupied in the electron-side flat band, or the hole-side flat band (i.e., three holes per moiré unit cell), the correlated peaks are found to counterintuitively grow with heating and maximize around 20 K - a signature of Pomeranchuk effect. Our multilayer heterostructure opens more opportunities to engineer complicated systems for investigating correlated phenomena.
    Superconducting properties of the C15-type Laves phase ZrIr2 with an Ir-based kagome lattice Hot!
    Qing-Song Yang(杨清松), Bin-Bin Ruan(阮彬彬), Meng-Hu Zhou(周孟虎), Ya-Dong Gu(谷亚东), Ming-Wei Ma(马明伟), Gen-Fu Chen(陈根富), and Zhi-An Ren(任治安)
    Chin. Phys. B, 2023, 32 (1):  017402.  DOI: 10.1088/1674-1056/aca3a2
    Abstract ( 388 )   HTML ( 12 )   PDF (2233KB) ( 320 )  
    We report systematic studies on superconducting properties of the Laves phase superconductor ZrIr$_2$. It crystallizes in a C15-type (cubic MgCu$_2$-type, space group $Fd\overline{3}m$) structure in which the Ir atoms form a kagome lattice, with cell parameters $a=b=c=7.3596(1)$ Å. Resistivity and magnetic susceptibility measurements indicate that ZrIr$_2$ is a type-II superconductor with a transition temperature of 4.0 K. The estimated lower and upper critical fields are 12.8 mT and 4.78 T, respectively. Heat capacity measurements confirm the bulk superconductivity in ZrIr$_2$. ZrIr$_2$ is found to possibly host strong-coupled s-wave superconductivity with the normalized specific heat change $\Delta C_{\rm e}/\gamma T_{\rm c} \sim 1.86$ and the coupling strength $\Delta_0/k_{\rm B}T_{\rm c} \sim 1.92$. First-principles calculations suggest that ZrIr$_2$ has three-dimensional Fermi surfaces with simple topologies, and the states at Fermi level mainly originate from the Ir-5d and Zr-4d orbitals. Similar to SrIr$_2$ and ThIr$_2$, spin--orbit coupling has dramatic influences on the band structure in ZrIr$_2$.
    MoS2/Si tunnel diodes based on comprehensive transfer technique
    Yi Zhu(朱翊), Hongliang Lv(吕红亮), Yuming Zhang(张玉明), Ziji Jia(贾紫骥), Jiale Sun(孙佳乐), Zhijun Lyu(吕智军), and Bin Lu(芦宾)
    Chin. Phys. B, 2023, 32 (1):  018501.  DOI: 10.1088/1674-1056/ac9604
    Abstract ( 340 )   HTML ( 3 )   PDF (647KB) ( 120 )  
    Due to the pristine interface of the 2D/3D face-tunneling heterostructure with an ultra-sharp doping profile, the 2D/3D tunneling field-effect transistor (TFET) is considered as one of the most promising low-power devices that can simultaneously obtain low off-state current (IOFF), high on-state current (ION) and steep subthreshold swing (SS). As a key element for the 2D/3D TFET, the intensive exploration of the tunnel diode based on the 2D/3D heterostructure is in urgent need. The transfer technique composed of the exfoliation and the release process is currently the most common approach to fabricating the 2D/3D heterostructures. However, the well-established transfer technique of the 2D materials is still unavailable. Only a small part of the irregular films can usually be obtained by mechanical exfoliation, while the choice of the chemical exfoliation may lead to the contamination of the 2D material films by the ions in the chemical etchants. Moreover, the deformation of the 2D material in the transfer process due to its soft nature also leads to the nonuniformity of the transferred film, which is one of the main reasons for the presence of the wrinkles and the stacks in the transferred film. Thus, the large-scale fabrication of the high-quality 2D/3D tunnel diodes is limited. In this article, a comprehensive transfer technique that can mend up the shortages mentioned above with the aid of the water and the thermal release tape (TRT) is proposed. Based on the method we proposed, the MoS2/Si tunnel diode is experimentally demonstrated and the transferred monolayer MoS2 film with the relatively high crystal quality is confirmed by atomic force microscopy (AFM), scanning electron microscopy (SEM), and Raman characterizations. Besides, the prominent negative differential resistance (NDR) effect is observed at room temperature, which verifies the relatively high quality of the MoS2/Si heterojunction. The bilayer MoS2/Si tunnel diode is also experimentally fabricated by repeating the transfer process we proposed, followed by the specific analysis of the electrical characteristics. This study shows the advantages of the transfer technique we proposed and indicates the great application foreground of the fabricated 2D/3D heterostructure for ultralow-power tunneling devices.
    Dynamic modeling of total ionizing dose-induced threshold voltage shifts in MOS devices
    Guangbao Lu(陆广宝), Jun Liu(刘俊), Chuanguo Zhang(张传国), Yang Gao(高扬), and Yonggang Li(李永钢)
    Chin. Phys. B, 2023, 32 (1):  018506.  DOI: 10.1088/1674-1056/ac9fc4
    Abstract ( 325 )   HTML ( 4 )   PDF (683KB) ( 131 )  
    The total ionizing dose (TID) effect is a key cause for the degradation/failure of semiconductor device performance under energetic-particle irradiation. We developed a dynamic model of mobile particles and defects by solving the rate equations and Poisson's equation simultaneously, to understand threshold voltage shifts induced by TID in silicon-based metal-oxide-semiconductor (MOS) devices. The calculated charged defect distribution and corresponding electric field under different TIDs are consistent with experiments. TID changes the electric field at the Si/SiO2 interface by inducing the accumulation of oxide charged defects nearby, thus shifting the threshold voltage accordingly. With increasing TID, the oxide charged defects increase to saturation, and the electric field increases following the universal 2/3 power law. Through analyzing the influence of TID on the interfacial electric field by different factors, we recommend that the radiation-hardened performance of devices can be improved by choosing a thin oxide layer with high permittivity and under high gate voltages.
    The coupled deep neural networks for coupling of the Stokes and Darcy-Forchheimer problems
    Jing Yue(岳靖), Jian Li(李剑), Wen Zhang(张文), and Zhangxin Chen(陈掌星)
    Chin. Phys. B, 2023, 32 (1):  010201.  DOI: 10.1088/1674-1056/ac7554
    Abstract ( 228 )   HTML ( 5 )   PDF (3138KB) ( 59 )  
    We present an efficient deep learning method called coupled deep neural networks (CDNNs) for coupling of the Stokes and Darcy-Forchheimer problems. Our method compiles the interface conditions of the coupled problems into the networks properly and can be served as an efficient alternative to the complex coupled problems. To impose energy conservation constraints, the CDNNs utilize simple fully connected layers and a custom loss function to perform the model training process as well as the physical property of the exact solution. The approach can be beneficial for the following reasons: Firstly, we sample randomly and only input spatial coordinates without being restricted by the nature of samples. Secondly, our method is meshfree, which makes it more efficient than the traditional methods. Finally, the method is parallel and can solve multiple variables independently at the same time. We present the theoretical results to guarantee the convergence of the loss function and the convergence of the neural networks to the exact solution. Some numerical experiments are performed and discussed to demonstrate performance of the proposed method.
    Anomalous diffusion in branched elliptical structure
    Kheder Suleiman, Xuelan Zhang(张雪岚), Erhui Wang(王二辉),Shengna Liu(刘圣娜), and Liancun Zheng(郑连存)
    Chin. Phys. B, 2023, 32 (1):  010202.  DOI: 10.1088/1674-1056/ac5c39
    Abstract ( 220 )   HTML ( 3 )   PDF (1089KB) ( 70 )  
    Diffusion in narrow curved channels with dead-ends as in extracellular space in the biological tissues, e.g., brain, tumors, muscles, etc. is a geometrically induced complex diffusion and is relevant to different kinds of biological, physical, and chemical systems. In this paper, we study the effects of geometry and confinement on the diffusion process in an elliptical comb-like structure and analyze its statistical properties. The ellipse domain whose boundary has the polar equation $\rho \left( \theta \right)=\frac{b}{\sqrt {1-e^{2}\cos^{2}\theta } }$ with $0<e<1$, $\theta \in \left[ 0,2\pi \right]$, and $b$ as a constant, can be obtained through stretched radius $r$ such that $\varUpsilon =r \rho \left( \theta \right)$ with $r\in \left[ 0,1 \right]$. We suppose that, for fixed radius $r=R$, an elliptical motion takes place and is interspersed with a radial motion inward and outward of the ellipse. The probability distribution function (PDF) in the structure and the marginal PDF and mean square displacement (MSD) along the backbone are obtained numerically. The results show that a transient sub-diffusion behavior dominates the process for a time followed by a saturating state. The sub-diffusion regime and saturation threshold are affected by the length of the elliptical channel lateral branch and its curvature.
    Inhibitory effect induced by fractional Gaussian noise in neuronal system
    Zhi-Kun Li(李智坤) and Dong-Xi Li(李东喜)
    Chin. Phys. B, 2023, 32 (1):  010203.  DOI: 10.1088/1674-1056/ac6332
    Abstract ( 235 )   HTML ( 2 )   PDF (1472KB) ( 87 )  
    We discover a phenomenon of inhibition effect induced by fractional Gaussian noise in a neuronal system. Firstly, essential properties of fractional Brownian motion (fBm) and generation of fractional Gaussian noise (fGn) are presented, and representative sample paths of fBm and corresponding spectral density of fGn are discussed at different Hurst indexes. Next, we consider the effect of fGn on neuronal firing, and observe that neuronal firing decreases first and then increases with increasing noise intensity and Hurst index of fGn by studying the time series evolution. To further quantify the inhibitory effect of fGn, by introducing the average discharge rate, we investigate the effects of noise and external current on neuronal firing, and find the occurrence of inhibitory effect about noise intensity and Hurst index of fGn at a certain level of current. Moreover, the inhibition effect is not easy to occur when the noise intensity and Hurst index are too large or too small. In view of opposite action mechanism compared with stochastic resonance, this suppression phenomenon is called inverse stochastic resonance (ISR). Finally, the inhibitory effect induced by fGn is further verified based on the inter-spike intervals (ISIs) in the neuronal system. Our work lays a solid foundation for future study of non-Gaussian-type noise on neuronal systems.
    Enhancement of electron-positron pairs in combined potential wells with linear chirp frequency
    Li Wang(王莉), Lie-Juan Li(李烈娟), Melike Mohamedsedik(麦丽开·麦提斯迪克), Rong An(安荣), Jing-Jing Li(李静静), Bo-Song Xie(谢柏松), and Feng-Shou Zhang(张丰收)
    Chin. Phys. B, 2023, 32 (1):  010301.  DOI: 10.1088/1674-1056/ac744b
    Abstract ( 226 )   HTML ( 2 )   PDF (741KB) ( 32 )  
    Effect of linear chirp frequency on the process of electron-positron pairs production from vacuum is investigated by the computational quantum field theory. With appropriate chirp parameters, the number of electrons created under combined potential wells can be increased by two or three times. In the low frequency region, frequency modulation excites interference effect and multiphoton processes, which promotes the generation of electron-positron pairs. In the high frequency region, high frequency suppression inhibits the generation of electron-positron pairs. In addition, for a single potential well, the number of created electron-positron pairs can be enhanced by several orders of magnitude in the low frequency region.
    Enhancement of charging performance of quantum battery via quantum coherence of bath
    Wen-Li Yu(于文莉), Yun Zhang(张允), Hai Li(李海), Guang-Fen Wei(魏广芬), Li-Ping Han(韩丽萍), Feng Tian(田峰), and Jian Zou(邹建)
    Chin. Phys. B, 2023, 32 (1):  010302.  DOI: 10.1088/1674-1056/ac728b
    Abstract ( 320 )   HTML ( 3 )   PDF (1224KB) ( 123 )  
    An open quantum battery (QB) model of a single qubit system charging in a coherent auxiliary bath (CAB) consisting of a series of independent coherent ancillae is considered. According to the collision charging protocol we derive a quantum master equation and obtain the analytical solution of QB in a steady state. We find that the full charging capacity (or the maximal extractable work (MEW)) of QB, in the weak QB-ancilla coupling limit, is positively correlated with the coherence magnitude of ancilla. Combining with the numerical simulations we compare with the charging properties of QB at finite coupling strength, such as the MEW, average charging power and the charging efficiency, when considering the bath to be a thermal auxiliary bath (TAB) and a CAB, respectively. We find that when the QB with CAB, in the weak coupling regime, is in fully charging, both its capacity and charging efficiency can go beyond its classical counterpart, and they increase with the increase of coherence magnitude of ancilla. In addition, the MEW of QB in the regime of relative strong coupling and strong coherent magnitude shows the oscillatory behavior with the charging time increasing, and the first peak value can even be larger than the full charging MEW of QB. This also leads to a much larger average charging power than that of QB with TAB in a short-time charging process. These features suggest that with the help of quantum coherence of CAB it becomes feasible to switch the charging schemes between the long-time slow charging protocol with large capacity and high efficiency and the short-time rapid charging protocol with highly charging power only by adjusting the coupling strength of QB-ancilla. This work clearly demonstrates that the quantum coherence of bath can not only serve as the role of "fuel" of QB to be utilized to improve the QB's charging performance but also provide an alternative way to integrate the different charging protocols into a single QB.
    Improving the teleportation of quantum Fisher information under non-Markovian environment
    Yan-Ling Li(李艳玲), Yi-Bo Zeng(曾艺博), Lin Yao(姚林), and Xing Xiao(肖兴)
    Chin. Phys. B, 2023, 32 (1):  010303.  DOI: 10.1088/1674-1056/ac6497
    Abstract ( 228 )   HTML ( 4 )   PDF (995KB) ( 77 )  
    Quantum teleportation is designed to send an unknown quantum state between two parties. In the perspective of remote quantum metrology, one may be interested in teleporting the information that is encoded by physical parameters synthesized by quantum Fisher information (QFI). However, the teleported QFI is often destroyed by the unavoidable interaction between the system and the environment. Here, we propose two schemes to improve the teleportation of QFI in the non-Markovian environment. One is to control the quantum system through the operations of weak measurement (WM) and corresponding quantum measurement reversal (QMR). The other is to modify the quantum system based on the monitoring result of the environment (i.e., environment-assisted measurement, EAM). It is found that, in the non-Markovian environment, these two schemes can improve the teleportation of QFI. By selecting the appropriate strengths of WM and QMR, the environment noise can be completely eliminated and the initial QFI is perfectly teleported. A comprehensive comparison shows that the second scheme not only has a higher probability of success than the first one, but also has a significant improvement of the teleported QFI.
    Transformation relation between coherence and entanglement for two-qubit states
    Qing-Yun Zhou(周晴云), Xiao-Gang Fan(范小刚), Fa Zhao(赵发), Dong Wang(王栋), and Liu Ye(叶柳)
    Chin. Phys. B, 2023, 32 (1):  010304.  DOI: 10.1088/1674-1056/ac7454
    Abstract ( 270 )   HTML ( 3 )   PDF (4755KB) ( 62 )  
    Entanglement and coherence are two important resources in quantum information theory. A question naturally arises: Is there some connection between them? We prove that the entanglement of formation and the first-order coherence of two-qubit states satisfy an inequality relation. Two-qubit pure state reaches the upper bound of this inequality. A large number of randomly generated states are used to intuitively verify the complementarity between the entanglement of formation and the first-order coherence. We give the maximum accessible coherence of two-qubit states. Our research results will provide a reliable theoretical basis for conversion of the two quantum resources.
    Temperature characterizations of silica asymmetric Mach-Zehnder interferometer chip for quantum key distribution
    Dan Wu(吴丹), Xiao Li(李骁), Liang-Liang Wang(王亮亮), Jia-Shun Zhang(张家顺), Wei Chen(陈巍), Yue Wang(王玥), Hong-Jie Wang(王红杰), Jian-Guang Li(李建光), Xiao-Jie Yin(尹小杰), Yuan-Da Wu(吴远大), Jun-Ming An(安俊明), and Ze-Guo Song(宋泽国)
    Chin. Phys. B, 2023, 32 (1):  010305.  DOI: 10.1088/1674-1056/ac9224
    Abstract ( 299 )   HTML ( 2 )   PDF (1164KB) ( 132 )  
    Quantum key distribution (QKD) system based on passive silica planar lightwave circuit (PLC) asymmetric Mach-Zehnder interferometers (AMZI) is characterized with thermal stability, low loss and sufficient integration scalability. However, waveguide stresses, both intrinsic and temperature-induced stresses, have significant impacts on the stable operation of the system. We have designed silica AMZI chips of 400 ps delay, with bend waveguides length equalized for both long and short arms to balance the stresses thereof. The temperature characteristics of the silica PLC AMZI chip are studied. The interference visibility at the single photon level is kept higher than 95% over a wide temperature range of 12 ℃. The delay time change is 0.321 ps within a temperature change of 40 ℃. The spectral shift is 0.0011 nm/0.1 ℃. Temperature-induced delay time and peak wavelength variations do not affect the interference visibility. The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.
    Tolerance-enhanced SU(1,1) interferometers using asymmetric gain
    Jian-Dong Zhang(张建东) and Shuai Wang(王帅)
    Chin. Phys. B, 2023, 32 (1):  010306.  DOI: 10.1088/1674-1056/ac981d
    Abstract ( 235 )   HTML ( 1 )   PDF (460KB) ( 63 )  
    SU(1,1) interferometers play an important role in quantum metrology. Previous studies focus on various inputs and detection strategies with symmetric gain. In this paper, we analyze a modified SU(1,1) interferometer using asymmetric gain. Two vacuum states are used as the input and on-off detection is performed at the output. In a lossless scenario, symmetric gain is the optimal selection and the corresponding phase sensitivity can achieve the Heisenberg limit as well as the quantum Cramer-Rao bound. In addition, we analyze the phase sensitivity with symmetric gain in the lossy scenario. The phase sensitivity is sensitive to internal losses but extremely robust against external losses. We address the optimal asymmetric gain and the results suggest that this method can improve the tolerance to internal losses. Our work may contribute to the practical development of quantum metrology.
    The shadow and observation appearance of black hole surrounded by the dust field in Rastall theory
    Xuan-Ran Zhu(朱轩然), Yun-Xian Chen(陈芸仙), Ping-Hui Mou(牟平辉), and Ke-Jian He(何柯腱)
    Chin. Phys. B, 2023, 32 (1):  010401.  DOI: 10.1088/1674-1056/ac6ee0
    Abstract ( 300 )   HTML ( 1 )   PDF (4027KB) ( 105 )  
    In the context of Rastall gravity, the shadow and observation intensity casted by the new Kiselev-like black hole with dust field have been numerically investigated. In this system, the Rastall parameter and surrounding dust field structure parameter have considerable consequences on the geometric structure of spacetime. Considering the photon trajectories near the black hole, we investigate the variation of the radii of photon sphere, event horizon and black hole shadow under the different related parameters. Furthermore, taking into account two different spherically symmetric accretion models as the only background light source, we also studied the observed luminosity and intensity of black holes. For the both spherical accretions background, the results show that the decrease or increase of the observed luminosity depends on the value range of relevant parameters, and the promotion effect is far less obvious than the attenuation effect on the observed intensity. One can find that the inner shadow region and outer bright region of the black hole wrapped by infalling accretion are significantly darker than those of the static model, which is closely related to the Doppler effect. In addition, the size of the shadow and the position of the photon sphere are always the same in the two accretion models, which means that the black hole shadow depend only on the geometry of spacetime, while the observation luminosity is affected by the form of accretion material and the related spacetime structure.
    A novel algorithm to analyze the dynamics of digital chaotic maps in finite-precision domain
    Chunlei Fan(范春雷) and Qun Ding(丁群)
    Chin. Phys. B, 2023, 32 (1):  010501.  DOI: 10.1088/1674-1056/ac785c
    Abstract ( 219 )   HTML ( 1 )   PDF (1096KB) ( 66 )  
    Chaotic maps are widely used to design pseudo-random sequence generators, chaotic ciphers, and secure communication systems. Nevertheless, the dynamic characteristics of digital chaos in finite-precision domain must be degraded in varying degrees due to the limited calculation accuracy of hardware equipment. To assess the dynamic properties of digital chaos, we design a periodic cycle location algorithm (PCLA) from a new perspective to analyze the dynamic degradation of digital chaos. The PCLA can divide the state-mapping graph of digital chaos into several connected subgraphs for the purpose of locating all fixed points and periodic limit cycles contained in a digital chaotic map. To test the versatility and availability of our proposed algorithm, the periodic distribution and security of 1-D logistic maps and 2-D Baker maps are analyzed in detail. Moreover, this algorithm is helpful to the design of anti-degradation algorithms for digital chaotic dynamics. These related studies can promote the application of chaos in engineering practice.
    Data encryption based on a 9D complex chaotic system with quaternion for smart grid
    Fangfang Zhang(张芳芳), Zhe Huang(黄哲), Lei Kou(寇磊), Yang Li(李扬), Maoyong Cao(曹茂永), and Fengying Ma(马凤英)
    Chin. Phys. B, 2023, 32 (1):  010502.  DOI: 10.1088/1674-1056/ac76b2
    Abstract ( 237 )   HTML ( 2 )   PDF (7032KB) ( 204 )  
    With the development of smart grid, operation and control of a power system can be realized through the power communication network, especially the power production and enterprise management business involve a large amount of sensitive information, and the requirements for data security and real-time transmission are gradually improved. In this paper, a new 9-dimensional (9D) complex chaotic system with quaternion is proposed for the encryption of smart grid data. Firstly, we present the mathematical model of the system, and analyze its attractors, bifurcation diagram, complexity, and 0-1 test. Secondly, the pseudo-random sequences are generated by the new chaotic system to encrypt power data. Finally, the proposed encryption algorithm is verified with power data and images in the smart grid, which can ensure the encryption security and real time. The verification results show that the proposed encryption scheme is technically feasible and available for power data and image encryption in smart grid.
    Firing activities in a fractional-order Hindmarsh-Rose neuron with multistable memristor as autapse
    Zhi-Jun Li(李志军), Wen-Qiang Xie(谢文强), Jin-Fang Zeng(曾金芳), and Yi-Cheng Zeng(曾以成)
    Chin. Phys. B, 2023, 32 (1):  010503.  DOI: 10.1088/1674-1056/ac65f7
    Abstract ( 205 )   HTML ( 1 )   PDF (5845KB) ( 84 )  
    Considering the fact that memristors have the characteristics similar to biological synapses, a fractional-order multistable memristor is proposed in this paper. It is verified that the fractional-order memristor has multiple local active regions and multiple stable hysteresis loops, and the influence of fractional-order on its nonvolatility is also revealed. Then by considering the fractional-order memristor as an autapse of Hindmarsh-Rose (HR) neuron model, a fractional-order memristive neuron model is developed. The effects of the initial value, external excitation current, coupling strength and fractional-order on the firing behavior are discussed by time series, phase diagram, Lyapunov exponent and inter spike interval (ISI) bifurcation diagram. Three coexisting firing patterns, including irregular asymptotically periodic (A-periodic) bursting, A-periodic bursting and chaotic bursting, dependent on the memristor initial values, are observed. It is also revealed that the fractional-order can not only induce the transition of firing patterns, but also change the firing frequency of the neuron. Finally, a neuron circuit with variable fractional-order is designed to verify the numerical simulations.
    Influence of coupling asymmetry on signal amplification in a three-node motif
    Xiaoming Liang(梁晓明), Chao Fang(方超), Xiyun Zhang(张希昀), and Huaping Lü(吕华平)
    Chin. Phys. B, 2023, 32 (1):  010504.  DOI: 10.1088/1674-1056/ac9363
    Abstract ( 224 )   HTML ( 1 )   PDF (461KB) ( 88 )  
    The three-node feedforward motif has been revealed to function as a weak signal amplifier. In this motif, two nodes (input nodes) receive a weak input signal and send it unidirectionally to the third node (output node). Here, we change the motif's unidirectional couplings (feedforward) to bidirectional couplings (feedforward and feedback working together). We find that a small asymmetric coupling, in which the feedforward effect is stronger than the feedback effect, may enable the three-node motif to go through two distinct dynamic transitions, giving rise to a double resonant signal response. We present an analytical description of the double resonance, which agrees with the numerical findings.
    Quantitative analysis of soliton interactions based on the exact solutions of the nonlinear Schrödinger equation
    Xuefeng Zhang(张雪峰), Tao Xu(许韬), Min Li(李敏), and Yue Meng(孟悦)
    Chin. Phys. B, 2023, 32 (1):  010505.  DOI: 10.1088/1674-1056/ac9822
    Abstract ( 232 )   HTML ( 2 )   PDF (4789KB) ( 137 )  
    We make a quantitative study on the soliton interactions in the nonlinear Schrödinger equation (NLSE) and its variable-coefficient (vc) counterpart. For the regular two-soliton and double-pole solutions of the NLSE, we employ the asymptotic analysis method to obtain the expressions of asymptotic solitons, and analyze the interaction properties based on the soliton physical quantities (especially the soliton accelerations and interaction forces); whereas for the bounded two-soliton solution, we numerically calculate the soliton center positions and accelerations, and discuss the soliton interaction scenarios in three typical bounded cases. Via some variable transformations, we also obtain the inhomogeneous regular two-soliton and double-pole solutions for the vcNLSE with an integrable condition. Based on the expressions of asymptotic solitons, we quantitatively study the two-soliton interactions with some inhomogeneous dispersion profiles, particularly discuss the influence of the variable dispersion function f(t) on the soliton interaction dynamics.
    Charge self-trapping in two strand biomolecules: Adiabatic polaron approach
    D Chevizovich, S Zdravković, A V Chizhov, and Z Ivić
    Chin. Phys. B, 2023, 32 (1):  010506.  DOI: 10.1088/1674-1056/ac70bc
    Abstract ( 229 )   HTML ( 1 )   PDF (970KB) ( 37 )  
    We investigate the properties of the excess charge (electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess charge with the phonon subsystem. The influence of overlap of the molecular orbitals between adjacent structure elements of the macromolecular chain on the soliton properties is discussed. Special attention is paid to the influence of the overlapping of the molecular orbitals between structure elements placed on the different chains. Using the literature values of the basic energy parameters of the two-chain biomolecular structures, possible types of soliton solutions are discussed.
    Memristor hyperchaos in a generalized Kolmogorov-type system with extreme multistability
    Xiaodong Jiao(焦晓东), Mingfeng Yuan(袁明峰), Jin Tao(陶金), Hao Sun(孙昊), Qinglin Sun(孙青林), and Zengqiang Chen(陈增强)
    Chin. Phys. B, 2023, 32 (1):  010507.  DOI: 10.1088/1674-1056/ac5e95
    Abstract ( 255 )   HTML ( 6 )   PDF (8301KB) ( 179 )  
    Memristor chaotic systems have aroused great attention in recent years with their potentials expected in engineering applications. In this paper, a five-dimension (5D) double-memristor hyperchaotic system (DMHS) is modeled by introducing two active magnetron memristor models into the Kolmogorov-type formula. The boundness condition of the proposed hyperchaotic system is proved. Coexisting bifurcation diagram and numerical verification explain the bistability. The rich dynamics of the system are demonstrated by the dynamic evolution map and the basin. The simulation results reveal the existence of transient hyperchaos and hidden extreme multistability in the presented DMHS. The NIST tests show that the generated signal sequence is highly random, which is feasible for encryption purposes. Furthermore, the system is implemented based on a FPGA experimental platform, which benefits the further applications of the proposed hyperchaos.
    Laboratory demonstration of geopotential measurement using transportable optical clocks
    Dao-Xin Liu(刘道信), Jian Cao(曹健), Jin-Bo Yuan(袁金波), Kai-Feng Cui(崔凯枫), Yi Yuan(袁易),Ping Zhang(张平), Si-Jia Chao(晁思嘉), Hua-Lin Shu(舒华林), and Xue-Ren Huang(黄学人)
    Chin. Phys. B, 2023, 32 (1):  010601.  DOI: 10.1088/1674-1056/ac6337
    Abstract ( 243 )   HTML ( 2 )   PDF (737KB) ( 93 )  
    We report an experimental demonstration of geopotential difference measurement using a pair of transportable $^{40}$Ca$^{+}$ optical clocks (TOC-729-1 and TOC-729-3) in the laboratory, each of them has an uncertainty of $1.3 \times 10^{-17}$ and an instability of $4.8 \times 10^{-15}/\sqrt{ \tau } $. Referenced to a stationary clock of TOC-729-1, the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm. After correcting the systematic shifts (including gravitational red shift), the two-clock frequency difference is measured to be $-0.7(2.2) \times 10^{-17}$, considering both the statistic $(1.0 \times 10^{-17})$ and the systematic $(1.9 \times 10^{-17})$ uncertainties. The frequency difference between these two clocks is within their respective uncertainties, verifying the reliability of transportable $^{40}$Ca$^{+}$ optical clocks at the low level of 10$^{-17}$.
    Theoretical calculations on Landé $g$-factors and quadratic Zeeman shift coefficients of $n$s$n$p $^{3} {P}^{o}_{0}$ clock states in Mg and Cd optical lattice clocks
    Benquan Lu(卢本全) and Hong Chang(常宏)
    Chin. Phys. B, 2023, 32 (1):  013101.  DOI: 10.1088/1674-1056/ac90b0
    Abstract ( 223 )   HTML ( 1 )   PDF (452KB) ( 130 )  
    The study of magnetic field effects on the clock transition of Mg and Cd optical lattice clocks is scarce. In this work, the hyperfine-induced Landé $g$-factors and quadratic Zeeman shift coefficients of the ${n{\rm s}n{\rm p}}$ $^3P^{\rm o}_0$ clock states for $^{111,113}$Cd and $^{25}$Mg were calculated by using the multi-configuration Dirac-Hartree-Fock theory. To obtain accurate values of these parameters, the impact of electron correlations and furthermore the Breit interaction and quantum electrodynamical effects on the Zeeman and hyperfine interaction matrix elements, and energy separations were investigated in detail. We also estimated the contributions from perturbing states to the Landé $g$-factors and quadratic Zeeman shift coefficients concerned so as to truncate the summation over the perturbing states without loss of accuracy. Our calculations provide important data for estimating the first- and second-order Zeeman shifts of the clock transition for the Cd and Mg optical lattice clocks.
    High-order harmonic generation of the cyclo[18]carbon molecule irradiated by circularly polarized laser pulse
    Shu-Shan Zhou(周书山), Yu-Jun Yang(杨玉军), Yang Yang(杨扬), Ming-Yue Suo(索明月), Dong-Yuan Li(李东垣), Yue Qiao(乔月), Hai-Ying Yuan(袁海颖), Wen-Di Lan(蓝文迪), and Mu-Hong Hu(胡木宏)
    Chin. Phys. B, 2023, 32 (1):  013201.  DOI: 10.1088/1674-1056/aca3a1
    Abstract ( 256 )   HTML ( 0 )   PDF (2608KB) ( 166 )  
    High-order harmonic generation of the cyclo[18]carbon (C18) molecule under few-cycle circularly polarized laser pulse is studied by time-dependent density functional theory. Compared with the harmonic emission of the ring molecule C6 H6 having similar ionization potential, the C18 molecule has higher efficiency and cutoff energy than C6 H6 with the same laser field parameters. Further researches indicate that the harmonic efficiency and cutoff energy of the C18 molecule increase gradually with the increase of the laser intensity of the driving laser or decrease of the wavelength, both are larger than those of the C6 H6 molecule. Through the analysis of the time-dependent evolution of the electronic wave packets, it is also found that the higher efficiency of harmonic generation can be attributed to the larger spatial scale of the C18 molecule, which leads to a greater chance for the ionized electrons from one atom to recombine with others of the parent molecule. Selecting the suitable driving laser pulse, it is demonstrated that high-order harmonic generation in the C18 molecule has a wide range of applications in producing circularly polarized isolated attosecond pulse.
    Space continuous atom laser in one dimension
    Yi Qin(秦毅), Xiao-Yang Shen(沈晓阳), Wei-Xuan Chang(常炜玄), and Lin Xia(夏林)
    Chin. Phys. B, 2023, 32 (1):  013701.  DOI: 10.1088/1674-1056/ac7861
    Abstract ( 232 )   HTML ( 0 )   PDF (589KB) ( 51 )  
    Cold atom physics in space station arouses a lot of interest of scientists. We investigate the dynamical output process of the space continuous atom laser by solving nonlinear Gross-Pitaevksii equations numerically. Slow-moving continuous atom beams in two directions are observed simultaneously. The slow-moving coherent atom beams can be used as a source of atom interferometer to realize long-time measurements. We also control the output of space atom laser by adjusting the output coupling strength.
    High gain and circularly polarized substrate integrated waveguide cavity antenna array based on metasurface
    Hao Bai(白昊), Guang-Ming Wang(王光明), and Xiao-Jun Zou(邹晓鋆)
    Chin. Phys. B, 2023, 32 (1):  014101.  DOI: 10.1088/1674-1056/ac6b22
    Abstract ( 247 )   HTML ( 0 )   PDF (3368KB) ( 63 )  
    Two substrate integrated waveguide (SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38% (4.05 GHz-5.95 GHz) and AR bandwidth of 24.9% (4.4 GHz-5.65 GHz). The bandwidth of the high gain antenna can reach 42.7% (3.95 GHz-6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.
    Evolution of polarization singularities accompanied by avoided crossing in plasmonic system
    Yi-Xiao Peng(彭一啸), Qian-Ju Song(宋前举), Peng Hu(胡鹏), Da-Jian Cui(崔大健), Hong Xiang(向红), and De-Zhuan Han(韩德专)
    Chin. Phys. B, 2023, 32 (1):  014201.  DOI: 10.1088/1674-1056/ac728d
    Abstract ( 241 )   HTML ( 0 )   PDF (2415KB) ( 73 )  
    The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied. The lateral inversion symmetry of the system, which breaks the in-plane inversion symmetry and up-down mirror symmetry simultaneously, yields abundant polarization states. A complete evolution process with geometry for the polarization states is traced. In the evolution, circularly polarized points (C points) can stem from 3 different processes. In addition to the previously reported processes occurring in an isolated band, a new type of C point appearing in two bands simultaneously due to the avoided band crossing, is observed. Unlike the dielectric system with a similar structure which only supports at-$\varGamma$ bound states in the continuum (BICs), accidental BICs off the $\varGamma$ point are realized in this plasmonic system. This work provides a new scheme of polarization manipulation for the plasmonic systems.
    Quantum properties of nonclassical states generated by an optomechanical system with catalytic quantum scissors
    Heng-Mei Li(李恒梅), Bao-Hua Yang(杨保华), Hong-Chun Yuan(袁洪春), and Ye-Jun Xu(许业军)
    Chin. Phys. B, 2023, 32 (1):  014202.  DOI: 10.1088/1674-1056/ac7206
    Abstract ( 223 )   HTML ( 0 )   PDF (1270KB) ( 53 )  
    A scheme is proposed to investigate the non-classical states generated by a quantum scissors device (QSD) operating on the the cavity mode of an optomechanical system. When the catalytic QSD acts on the cavity mode of the optomechanical system, the resulting state contains only the vacuum, single-photon and two-photon states depending upon the coupling parameter of the optomechanical system as well as the transmission coefficients of beam splitters (BSs). Especially, the output state is just a class of multicomponent cat state truncations at time t=2π by choosing the appropriate value of coupling parameter. We discuss the success probability of such a state and the fidelity between the output state and input state via QSD. Then the linear entropy is used to investigate the entanglement between the two subsystems, finding that QSD operation can enhance their entanglement degree. Furthermore, we also derive the analytical expression of the Wigner function (WF) for the cavity mode via QSD and numerically analyze the WF distribution in phase space at time t=2π. These results show that the high non-classicality of output state can always be achieved by modulating the coupling parameter of the optomechanical system as well as the transmittance of BSs.
    Effect of laser focus in two-color synthesized waveform on generation of soft x-ray high harmonics
    Yanbo Chen(陈炎波), Baochang Li(李保昌), Xuhong Li(李胥红), Xiangyu Tang(唐翔宇), Chi Zhang(张弛), and Cheng Jin(金成)
    Chin. Phys. B, 2023, 32 (1):  014203.  DOI: 10.1088/1674-1056/ac8cea
    Abstract ( 247 )   HTML ( 0 )   PDF (2522KB) ( 235 )  
    Synthesis of multi-color laser pulses has been developed as a promising way to improve low conversion efficiency of high-order harmonic generation (HHG). Here we systematically study the effect of laser focus in a two-color waveform on generation of macroscopic HHG in soft x-rays. We find that the dependence of HHG yields on laser focus at low or high gas pressure is sensitive to the characteristics of single-atom harmonic response, in which "short"-or "long"-trajectory emissions can be selectively controlled by changing the waveform of two-color synthesized laser pulse. We uncover the phase-matching mechanism of HHG in the gas medium by examining the propagation of the two-color waveform and the evolution of time-frequency emissions of high-harmonic field. We further reveal that the nonlinear effects, such as geometric phase, atomic dispersion, and plasma defocusing, are responsible for modification of two-color waveform upon propagation. This work can be used to find better macroscopic conditions for generating soft x-ray HHG by employing two-color optimized waveforms.
    Design of a coated thinly clad chalcogenide long-period fiber grating refractive index sensor based on dual-peak resonance near the phase matching turning point
    Qianyu Qi(齐倩玉), Yaowei Li(李耀威), Ting Liu(刘婷), Peiqing Zhang(张培晴),Shixun Dai(戴世勋), and Tiefeng Xu(徐铁峰)
    Chin. Phys. B, 2023, 32 (1):  014204.  DOI: 10.1088/1674-1056/ac6338
    Abstract ( 227 )   HTML ( 0 )   PDF (827KB) ( 33 )  
    A novel method for designing chalcogenide long-period fiber grating (LPFG) sensors based on the dual-peak resonance effect of the LPFG near the phase matching turning point (PMTP) is presented. Refractive index sensing in a high-refractive-index chalcogenide fiber is achieved with a coated thinly clad film. The dual-peak resonant characteristics near the PMTP and the refractive index sensing properties of the LPFG are analyzed first by the phase-matching condition of the LPFG. The effects of film parameters and cladding radius on the sensitivity of refractive index sensing are further discussed. The sensor is optimized by selecting the appropriate film parameters and cladding radius. Simulation results show that the ambient refractive index sensitivity of a dual-peak coated thinly clad chalcogenide LPFG at the PMTP can be 2400 nm/RIU, which is significantly higher than that of non-optimized gratings. It has great application potential in the field of chemical sensing and biosensors.
    Optical pulling force on nanoparticle clusters with gain due to Fano-like resonance
    Jiangnan Ma(马江南), Feng Lv(冯侣), Guofu Wang(王国富), Zhifang Lin(林志方), Hongxia Zheng(郑红霞), and Huajin Chen(陈华金)
    Chin. Phys. B, 2023, 32 (1):  014205.  DOI: 10.1088/1674-1056/ac9de5
    Abstract ( 262 )   HTML ( 2 )   PDF (1001KB) ( 94 )  
    We demonstrate that, in a simple linearly-polarized plane wave, the optical pulling forces on nanoparticle clusters with gain can be induced by the Fano-like resonance. The numerical results based on the full-wave calculation show that the optical pulling forces can be attributed to the recoil forces for the nanoparticle clusters composed of dipolar nanoparticles with three different configurations. Interestingly, the recoil forces giving rise to optical pulling forces are exactly dominated by the coupling term between the electric and magnetic dipoles excited in the nanoparticle clusters, while other higher-order terms have a negligible contribution. In addition, the optical pulling force can be tailored by modulating the Fano-like resonance via either the particle size or the gain magnitude, offering an alternative freedom degree for optical manipulations of particle clusters.
    Effect of porous surface layer on wave propagation in elastic cylinder immersed in fluid
    Na-Na Su(苏娜娜), Qing-Bang Han(韩庆邦), Ming-Lei Shan(单鸣雷), and Cheng Yin(殷澄)
    Chin. Phys. B, 2023, 32 (1):  014301.  DOI: 10.1088/1674-1056/ac6ee6
    Abstract ( 203 )   HTML ( 0 )   PDF (2523KB) ( 39 )  
    To study the damage to an elastic cylinder immersed in fluid, a model of an elastic cylinder wrapped with a porous medium immersed in fluid is designed. This structure can both identify the properties of guided waves in a more practical model and address the relationship between the cylinder damage degree and the surface and surrounding medium. The principal motivation is to perform a detailed quantitative analysis of the longitudinal mode and flexural mode in an elastic cylinder wrapped with a porous medium immersed in fluid. The frequency equations for the propagation of waves are derived each for a pervious surface and an impervious surface by employing Biot theory. The influences of the various parameters of the porous medium wrapping layer on the phase velocity and attenuation are discussed. The results show that the influences of porosity on the dispersion curves of guided waves are much more significant than those of thickness, whereas the phase velocity is independent of the static permeability. There is an apparent "mode switching" between the two low-order modes. The characteristics of attenuation are in good agreement with the results from the dispersion curves. This work can support future studies for optimizing the theory on detecting the damage to cylinder or pipeline.
    Effects of adjacent bubble on spatiotemporal evolutions of mechanical stresses surrounding bubbles oscillating in tissues
    Qing-Qin Zou(邹青钦), Shuang Lei(雷双), Zhang-Yong Li(李章勇), and Dui Qin(秦对)
    Chin. Phys. B, 2023, 32 (1):  014302.  DOI: 10.1088/1674-1056/ac70ba
    Abstract ( 240 )   HTML ( 1 )   PDF (1438KB) ( 53 )  
    The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues. Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.
    Quantitative ultrasound brain imaging with multiscale deconvolutional waveform inversion
    Yu-Bing Li(李玉冰), Jian Wang(王建), Chang Su(苏畅), Wei-Jun Lin(林伟军), Xiu-Ming Wang(王秀明), and Yi Luo(骆毅)
    Chin. Phys. B, 2023, 32 (1):  014303.  DOI: 10.1088/1674-1056/ac6dad
    Abstract ( 226 )   HTML ( 4 )   PDF (5845KB) ( 105 )  
    High-resolution images of human brain are critical for monitoring the neurological conditions in a portable and safe manner. Sound speed mapping of brain tissues provides unique information for such a purpose. In addition, it is particularly important for building digital human acoustic models, which form a reference for future ultrasound research. Conventional ultrasound modalities can hardly image the human brain at high spatial resolution inside the skull due to the strong impedance contrast between hard tissue and soft tissue. We carry out numerical experiments to demonstrate that the time-domain waveform inversion technique, originating from the geophysics community, is promising to deliver quantitative images of human brains within the skull at a sub-millimeter level by using ultra-sound signals. The successful implementation of such an approach to brain imaging requires the following items: signals of sub-megahertz frequencies transmitting across the inside of skull, an accurate numerical wave equation solver simulating the wave propagation, and well-designed inversion schemes to reconstruct the physical parameters of targeted model based on the optimization theory. Here we propose an innovative modality of multiscale deconvolutional waveform inversion that improves ultrasound imaging resolution, by evaluating the similarity between synthetic data and observed data through using limited length Wiener filter. We implement the proposed approach to iteratively update the parametric models of the human brain. The quantitative imaging method paves the way for building the accurate acoustic brain model to diagnose associated diseases, in a potentially more portable, more dynamic and safer way than magnetic resonance imaging and x-ray computed tomography.
    Heat transport properties within living biological tissues with temperature-dependent thermal properties
    Ying-Ze Wang(王颖泽), Xiao-Yu Lu(陆晓宇), and Dong Liu(刘栋)
    Chin. Phys. B, 2023, 32 (1):  014401.  DOI: 10.1088/1674-1056/ac6b29
    Abstract ( 220 )   HTML ( 0 )   PDF (539KB) ( 28 )  
    Understanding of the heat transport within living biological tissues is crucial to effective heat treatments. The heat transport properties of living biological tissues with temperature-dependent properties are explored in this paper. Taking into account of variable physical properties, the governing equation of temperature is first derived in the context of the dual-phase-lags model (DPL). An effective method, according to the Laplace transform and a linearization technique, is then employed to solve this nonlinear governing equation. The temperature distribution of a biological tissue exposed to a pulsed heat flux on its exterior boundary, which frequently happens in various heat treatments, is predicted and analyzed. The results state that a lower temperature can be predicted when temperature dependence is considered in the heating process. The contributions of key thermal parameters are different and dependent on the ratio of phase lag and the amplitude of the exterior pulsed heat flux.
    Traffic flow of connected and automated vehicles at lane drop on two-lane highway: An optimization-based control algorithm versus a heuristic rules-based algorithm
    Huaqing Liu(刘华清), Rui Jiang(姜锐), Junfang Tian(田钧方), and Kaixuan Zhu(朱凯旋)
    Chin. Phys. B, 2023, 32 (1):  014501.  DOI: 10.1088/1674-1056/ac9369
    Abstract ( 239 )   HTML ( 2 )   PDF (11426KB) ( 116 )  
    This paper investigates traffic flow of connected and automated vehicles at lane drop on two-lane highway. We evaluate and compare performance of an optimization-based control algorithm (OCA) with that of a heuristic rules-based algorithm (HRA). In the OCA, the average speed of each vehicle is maximized. In the HRA, virtual vehicle and restriction of the command acceleration caused by the virtual vehicle are introduced. It is found that (i) capacity under the HRA (denoted as CH) is smaller than capacity under the OCA; (ii) the travel delay is always smaller under the OCA, but driving is always much more comfortable under the HRA; (iii) when the inflow rate is smaller than CH, the HRA outperforms the OCA with respect to the fuel consumption and the monetary cost; (iv) when the inflow rate is larger than CH, the HRA initially performs better with respect to the fuel consumption and the monetary cost, but the OCA would become better after certain time. The spatiotemporal pattern and speed profile of traffic flow are presented, which explains the reason underlying the different performance. The study is expected to help for better understanding of the two different types of algorithm.
    Linear analysis of plasma pressure-driven mode in reversed shear cylindrical tokamak plasmas
    Ding-Zong Zhang(张定宗), Xu-Ming Feng(冯旭铭), Jun Ma(马骏), Wen-Feng Guo(郭文峰), Yan-Qing Huang(黄艳清), and Hong-Bo Liu(刘洪波)
    Chin. Phys. B, 2023, 32 (1):  015201.  DOI: 10.1088/1674-1056/ac70b4
    Abstract ( 239 )   HTML ( 0 )   PDF (923KB) ( 73 )  
    The linear behavior of the dominant unstable mode ($m=2$, $n=1$) and its high order harmonics ($m=2n$, $n\ge 2$) are numerically investigated in a reversed magnetic shear cylindrical plasma with two $q=2$ rational surfaces on the basis of the non-reduced magnetohydrodynamics (MHD) equations. The results show that with low beta (beta is defined as the ratio of plasma pressure to magnetic field pressure), the dominant mode is a classical double tearing mode (DTM). However, when the beta is sufficiently large, the mode is driven mainly by plasma pressure. In such a case, both the linear growth rate and mode structures are strongly affected by pressure, while almost independent of the resistivity. This means that the dominant mode undergoes a transition from DTM to pressure-driven mode with the increase of pressure, which is consistent with the experimental result in ASDEX Upgrade. The simulations also show that the distance between two rational surfaces has an important influence on the pressure needed in mode transition. The larger the distance between two rational surfaces, the larger the pressure for driving the mode transition is. Motivated by the phenomena that the high-$m$ modes may dominate over low-$m$ modes at small inter-resonance distance, the high-$m$ modes with different pressures and $q$ profiles are studied too.
    Pressure-induced stable structures and physical properties of Sr-Ge system
    Shuai Han(韩帅), Shuai Duan(段帅), Yun-Xian Liu(刘云仙), Chao Wang(王超), Xin Chen(陈欣), Hai-Rui Sun(孙海瑞), and Xiao-Bing Liu(刘晓兵)
    Chin. Phys. B, 2023, 32 (1):  016101.  DOI: 10.1088/1674-1056/ac6db5
    Abstract ( 225 )   HTML ( 1 )   PDF (2251KB) ( 67 )  
    We have systematically investigated the structures of Sr-Ge system under pressures up to 200 GPa and found six stable stoichiometric structures, they being Sr$_{3}$Ge, Sr$_{2}$Ge, SrGe, SrGe$_{2}$, SrGe$_{3}$, and SrGe$_{4}$. We demonstrate the interesting structure evolution behaviors in Sr-Ge system with the increase of germanium content, Ge atoms arranging into isolated anions in Sr$_{3}$Ge, chains in Sr$_{2}$Ge, square units in SrGe, trigonal units and hexahedrons in SrGe$_{2}$, cages in SrGe$_{3}$, hexagons and Ge$_{8}$ rings in SrGe$_{4}$. The structural diversity produces various manifestations of electronic structures, which is of benefit to electrical transportation. Among them, these novel phases with metallic structures show superconductivity (maximum $T_{\rm c}\sim 8.94$ K for Pmmn Sr$_{3}$Ge). Notably, the n-type semiconducting Pnma SrGe$_{2}$ structure exhibits high Seebeck coefficient and excellent electrical conductivity along the $y$ direction, leading to a high $ZT$ value up to 1.55 at 500 K, which can be potential candidates as high-performance thermoelectrics. Our results will enable the development of fundamental science in condensed matter physics and potential applications in novel electronics or thermoelectric materials.
    Molecular dynamics simulation of interaction between nanorod and phospholipid molecules bilayer
    Xin Wang(王鑫), Xiang-Qin Li(李香琴), Tian-Qing Liu(刘天庆), Li-Dan Zhao(赵丽丹), Ke-Dong Song(宋克东), and Dan Ge(葛丹)
    Chin. Phys. B, 2023, 32 (1):  016201.  DOI: 10.1088/1674-1056/ac6ed8
    Abstract ( 315 )   HTML ( 2 )   PDF (4304KB) ( 153 )  
    Natural and artificially prepared nanorods' surfaces have proved to have good bactericidal effect and self-cleaning property. In order to investigate whether nanorods can kill the enveloped virus, like destroying bacterial cell, we study the interaction between nanorods and virus envelope by establishing the models of nanorods with different sizes as well as the planar membrane and vesicle under the Dry Martini force field of molecular dynamics simulation. The results show that owing to the van der Waals attraction between nanorods and the tail hydrocarbon chain groups of phospholipid molecules, the phospholipid molecules on virus envelope are adsorbed to nanorods on a large scale. This process will increase the surface tension of lipid membrane and reduce the order of lipid molecules, resulting in irreparable damage to planar lipid membrane. Nanorods with different diameters have different effects on vesicle envelope, the larger the diameter of nanorod, the weaker the van der Waals effect on the unit cross-sectional area is and the smaller the degree of vesicle deformation. There is synergy between the nanorods in the nanorod array, which can enhance the speed and scale of lipid adsorption. The vesicle adsorbed in the array are difficult to desorb, and even if desorbed, vesicle will be seriously damaged. The deformation rate of the vesicle adsorbed in the nanorod array exceeds 100%, implying that the nanorod array has a strong destructive effect on the vesicle. This preliminarily proves the feasibility of nanorod array on a surface against enveloped virus, and provides a reference for the design of corresponding nanorods surface.
    Dramatic reduction in dark current of β-Ga2O3 ultraviolet photodectors via β-(Al0.25Ga0.75)2O3 surface passivation
    Jian-Ying Yue(岳建英), Xue-Qiang Ji(季学强), Shan Li(李山), Xiao-Hui Qi(岐晓辉), Pei-Gang Li(李培刚), Zhen-Ping Wu(吴真平), and Wei-Hua Tang(唐为华)
    Chin. Phys. B, 2023, 32 (1):  016701.  DOI: 10.1088/1674-1056/ac8a8e
    Abstract ( 209 )   HTML ( 0 )   PDF (2258KB) ( 107 )  
    Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based on β -(Al0.25Ga0.75)2O3/β -Ga2O3 film grown by metal-organic chemical vapor deposition. It was known that various surface states increase dark current and a large number of defects can hinder the transport of carriers, resulting in low switching ratio and low responsivity of the device. In this work, β -(Al0.25Ga0.75)2O3 films are used as surface passivation materials. Owning to its wide band gap, we obtain excellent light transmission and high lattice matching with β -Ga2O3. We explore the change and mechanism of the detection performance of the β -Ga2O3 detector after β -(Al0.25Ga0.75)2O3 surface passivation. It is found that under the illumination with 254 nm light at bias 5 V, the β -(Al0.25Ga0.75)2O3/β -Ga2O3 photodetectors show dark current of just 18 pA and high current on/off ratio of 2.16×105. The dark current is sharply reduced about 50 times after passivation of the β -Ga2O3 surface, and current on/off ratio increases by approximately 2 times. It is obvious that β -Ga2O3 detectors with β -(Al0.25Ga0.75)2O3 surface passivation can offer superior detector performance.
    Site selective 5f electronic correlations in β-uranium
    Ruizhi Qiu(邱睿智), Liuhua Xie(谢刘桦), and Li Huang(黄理)
    Chin. Phys. B, 2023, 32 (1):  017101.  DOI: 10.1088/1674-1056/ac76ad
    Abstract ( 209 )   HTML ( 2 )   PDF (1496KB) ( 17 )  
    We investigate the electronic structure of $\beta$-uranium, which has five nonequivalent atomic sites in its unit cell, by means of the density functional theory plus Hubbard-$U$ correction with $U$ from linear response calculation. It is found that the 5f electronic correlations in $\beta$-uranium are moderate. More interestingly, their strengths are site selective, depending on the local atomic environment of the present uranium atom. As a consequence, the occupation matrices and partial 5f density of states of $\beta$-uranium manifest site dependence. In addition, the complicate experimental structure of $\beta$-uranium could be well reproduced within this theoretical framework.
    Formation of quaternary all-d-metal Heusler alloy by Co doping fcc type Ni2MnV and mechanical grinding induced B2-fcc transformation
    Lu Peng(彭璐), Qiangqiang Zhang(张强强), Na Wang(王娜), Zhonghao Xia(夏中昊), Yajiu Zhang(张亚九),Zhigang Wu(吴志刚), Enke Liu(刘恩克), and Zhuhong Liu(柳祝红)
    Chin. Phys. B, 2023, 32 (1):  017102.  DOI: 10.1088/1674-1056/ac5e94
    Abstract ( 329 )   HTML ( 2 )   PDF (2088KB) ( 93 )  
    The structure of the all-d-metal alloy Ni$_{50-x}$Co$_{x}$Mn$_{25}$V$_{25}$ ($x = 0$-50) is investigated by using theoretical and experimental methods. The first-principles calculations indicate that the most stable structure of the Ni$_{2}$MnV alloy is face-centered cubic (fcc) type structure with ferrimagnetic state and the equilibrium lattice constant is 3.60 Å, which is in agreement with the experimental result. It is remarkable that replacing partial Ni with Co can turn the alloy from the fcc structure to the B2-type Heusler structure as Co content $x > 37$ by using the melting spinning method, implying that the d-d hybridization between Co/Mn elements and low-valent elements V stabilizes the Heusler structure. The Curie temperature $T_{\rm C}$ of all-d-metal Heuser alloy Ni$_{50-x}$Co$_{x}$Mn$_{25}$V$_{25}$ ($x > 37$) increases almost linearly with the increase of Co due to that the interaction of Co-Mn is stronger than that of Ni-Mn. A magnetic transition from ferromagnetic state to weak magnetic state accompanying with grinding stress induced transformation from B2 to the dual-phase of B2 and fcc has been observed in these all-d-metal Heusler alloys. This phase transformation and magnetic change provide a guide to overcome the brittleness and make the all-d-metal Heusler alloy interesting in stress and magnetic driving structural transition.
    Interface-induced topological phase and doping-modulated bandgap of two-dimensioanl graphene-like networks
    Ningjing Yang(杨柠境), Hai Yang(杨海), and Guojun Jin(金国钧)
    Chin. Phys. B, 2023, 32 (1):  017201.  DOI: 10.1088/1674-1056/ac904d
    Abstract ( 248 )   HTML ( 1 )   PDF (3409KB) ( 72 )  
    Biphenylene is a new topological material that has attracted much attention recently. By amplifying its size of unit cell, we construct a series of planar structures as homogeneous carbon allotropes in the form of polyphenylene networks. We first use the low-energy effective model to prove the topological three periodicity for these allotropes. Then, through first-principles calculations, we show that the topological phase has the Dirac point. As the size of per unit cell increases, the influence of the quaternary rings decreases, leading to a reduction in the anisotropy of the system, and the Dirac cone undergoes a transition from type II to type I. We confirm that there are two kinds of non-trivial topological phases with gapless and gapped bulk dispersion. Furthermore, we add a built-in electric field to the gapless system by doping with B and N atoms, which opens a gap for the bulk dispersion. Finally, by manipulating the built-in electric field, the dispersion relations of the edge modes will be transformed into a linear type. These findings provide a hopeful approach for designing the topological carbon-based materials with controllable properties of edge states.
    Effects of preparation parameters on growth and properties of β-Ga2O3 film
    Zi-Hao Chen(陈子豪), Yong-Sheng Wang(王永胜), Ning Zhang(张宁), Bin Zhou(周兵), Jie Gao(高洁), Yan-Xia Wu(吴艳霞), Yong Ma(马永), Hong-Jun Hei(黑鸿君), Yan-Yan Shen(申艳艳), Zhi-Yong He(贺志勇), and Sheng-Wang Yu(于盛旺)
    Chin. Phys. B, 2023, 32 (1):  017301.  DOI: 10.1088/1674-1056/ac728c
    Abstract ( 242 )   HTML ( 0 )   PDF (3636KB) ( 222 )  
    The Ga$_{2}$O$_{3}$ films are deposited on the Si and quartz substrates by magnetron sputtering, and annealing. The effects of preparation parameters (such as argon-oxygen flow ratio, sputtering power, sputtering time and annealing temperature) on the growth and properties ($e.g.$, surface morphology, crystal structure, optical and electrical properties of the films) are studied by x-ray diffractometer (XRD), scanning electron microscope (SEM), and ultraviolet-visible spectrophotometer (UV-Vis). The results show that the thickness, crystallization quality and surface roughness of the $\beta $-Ga$_{2}$O$_{3}$ film are influenced by those parameters. All $\beta $-Ga$_{2}$O$_{3 }$films show good optical properties. Moreover, the value of bandgap increases with the enlarge of the percentage of oxygen increasing, and decreases with the increase of sputtering power and annealing temperature, indicating that the bandgap is related to the quality of the film and affected by the number of oxygen vacancy defects. The $I$-$V$ curves show that the Ohmic behavior between metal and $\beta $-Ga$_{2}$O$_{3}$ films is obtained at 900 ${^\circ}$C. Those results will be helpful for the further research of $\beta $-Ga$_{2}$O$_{3}$ photoelectric semiconductor.
    Polyhedral silver clusters as single molecule ammonia sensor based on charge transfer-induced plasmon enhancement
    Jiu-Huan Chen(陈九环) and Xin-Lu Cheng(程新路)
    Chin. Phys. B, 2023, 32 (1):  017302.  DOI: 10.1088/1674-1056/ac6daf
    Abstract ( 203 )   HTML ( 1 )   PDF (2430KB) ( 37 )  
    The unique plasmon resonance characteristics of nanostructures based on metal clusters have always been the focus of various plasmon devices and different applications. In this work, the plasmon resonance phenomena of polyhedral silver clusters under the adsorption of NH3, N2, H2, and CH4 molecules are studied by using time-dependent density functional theory. Under the adsorption of NH3, the tunneling current of silver clusters changes significantly due to the charge transfer from NH3 to silver clusters. However, the effects of N2, H2, and CH4 adsorption on the tunneling current of silver clusters are negligible. Our results indicate that these silver clusters exhibit excellent selectivities and sensitivities for NH3 detection. These findings confirm that the silver cluster is a promising NH3 sensor and provide a new method for designing high-performance sensors in the future.
    Nonlinear optical rectification of GaAs/Ga1-xAlxAs quantum dots with Hulthén plus Hellmann confining potential
    Yi-Ming Duan(段一名) and Xue-Chao Li(李学超)
    Chin. Phys. B, 2023, 32 (1):  017303.  DOI: 10.1088/1674-1056/ac70bf
    Abstract ( 258 )   HTML ( 1 )   PDF (2256KB) ( 33 )  
    We investigate the nonlinear optical rectification (NOR) of spherical quantum dots (QDs) under Hulthén plus Hellmann confining potential with the external tuning elements. Energy and wavefunction are determined by using the Nikiforov-Uvarov method. Expression for the NOR coefficient is derived by the density matrix theory. The results show that the applied external elements and internal parameters of this system have a strong influence on intraband nonlinear optical properties. It is hopeful that this tuning of the nonlinear optical properties of GaAs/Ga1-xAlxAs QDs can make a greater contribution to preparation of new functional optical devices.
    High-performance artificial neurons based on Ag/MXene/GST/Pt threshold switching memristors
    Xiao-Juan Lian(连晓娟), Jin-Ke Fu(付金科), Zhi-Xuan Gao(高志瑄),Shi-Pu Gu(顾世浦), and Lei Wang(王磊)
    Chin. Phys. B, 2023, 32 (1):  017304.  DOI: 10.1088/1674-1056/ac673f
    Abstract ( 316 )   HTML ( 0 )   PDF (3923KB) ( 77 )  
    Threshold switching (TS) memristors can be used as artificial neurons in neuromorphic systems due to their continuous conductance modulation, scalable and energy-efficient properties. In this paper, we propose a low power artificial neuron based on the Ag/MXene/GST/Pt device with excellent TS characteristics, including a low set voltage (0.38 V) and current (200 nA), an extremely steep slope (< 0.1 mV/dec), and a relatively large off/on ratio (> 103). Besides, the characteristics of integrate and fire neurons that are indispensable for spiking neural networks have been experimentally demonstrated. Finally, its memristive mechanism is interpreted through the first-principles calculation depending on the electrochemical metallization effect.
    High frequency doubling efficiency THz GaAs Schottky barrier diode based on inverted trapezoidal epitaxial cross-section structure
    Xiaoyu Liu(刘晓宇), Yong Zhang(张勇), Haoran Wang(王皓冉), Haomiao Wei(魏浩淼),Jingtao Zhou(周静涛), Zhi Jin(金智), Yuehang Xu(徐跃杭), and Bo Yan(延波)
    Chin. Phys. B, 2023, 32 (1):  017305.  DOI: 10.1088/1674-1056/ac6162
    Abstract ( 248 )   HTML ( 0 )   PDF (3641KB) ( 77 )  
    A high-performance terahertz Schottky barrier diode (SBD) with an inverted trapezoidal epitaxial cross-sectional structure featuring high varactor characteristics and reverse breakdown characteristics is reported in this paper. Inductively coupled plasma dry etching and dissolution wet etching are used to define the profile of the epitaxial layer, by which the voltage-dependent variation trend of the thickness of the metal-semiconductor contact depletion layer is modified. The simulation of the inverted trapezoidal epitaxial cross-section SBD is also conducted to explain the physical mechanism of the electric field and space charge region area. Compared with the normal structure, the grading coefficient M increases from 0.47 to 0.52, and the capacitance modulation ratio (Cmax/Cmin) increases from 6.70 to 7.61. The inverted trapezoidal epitaxial cross-section structure is a promising approach to improve the variable-capacity ratio by eliminating the accumulation of charge at the Schottky electrode edge. A 190 GHz frequency doubler based on the inverted trapezoidal epitaxial cross-section SBD also shows a doubling efficiency of 35% compared to that 30% of a normal SBD.
    Design optimization of high breakdown voltage vertical GaN junction barrier Schottky diode with high-K/low-K compound dielectric structure
    Kuiyuan Tian(田魁元), Yong Liu(刘勇), Jiangfeng Du(杜江锋), and Qi Yu(于奇)
    Chin. Phys. B, 2023, 32 (1):  017306.  DOI: 10.1088/1674-1056/ac8e99
    Abstract ( 251 )   HTML ( 1 )   PDF (1537KB) ( 112 )  
    A vertical junction barrier Schottky diode with a high-$K$/low-$K$ compound dielectric structure is proposed and optimized to achieve a high breakdown voltage (BV). There is a discontinuity of the electric field at the interface of high-$K$ and low-$K$ layers due to the different dielectric constants of high-$K$ and low-$K$ dielectric layers. A new electric field peak is introduced in the n-type drift region of junction barrier Schottky diode (JBS), so the distribution of electric field in JBS becomes more uniform. At the same time, the effect of electric-power line concentration at the p-n junction interface is suppressed due to the effects of the high-$K$ dielectric layer and an enhancement of breakdown voltage can be achieved. Numerical simulations demonstrate that GaN JBS with a specific on-resistance ($R_{\rm on, sp}$) of 2.07 m$\Omega\cdot$cm$^{2}$ and a BV of 4171 V which is 167% higher than the breakdown voltage of the common structure, resulting in a high figure-of-merit (FOM) of 8.6 GW/cm$^{2}$, and a low turn-on voltage of 0.6 V.
    Majorana zero modes induced by skyrmion lattice
    Dong-Yang Jing(靖东洋), Huan-Yu Wang(王寰宇), Wen-Xiang Guo(郭文祥), and Wu-Ming Liu(刘伍明)
    Chin. Phys. B, 2023, 32 (1):  017401.  DOI: 10.1088/1674-1056/ac6ee7
    Abstract ( 239 )   HTML ( 0 )   PDF (2229KB) ( 36 )  
    One-dimensional s-wave superconductor with spin-orbit coupling is a platform for the realization of Majorana zero modes. The spin-exchange with the magnetic skyrmion lattice can induce spin-orbit coupling in a s-wave superconductor system and the effects are different from the constant spin-orbit coupling. The strength of the effective spin-orbit coupling as well as the rich topoloigcal phase diagram are directly connected to the radius of the skyrmion lattice R. We obtain the rich topological phase diagram of this system with different skyrmion lattice radii by numerically evaluating the spectrum of the system under the periodic boundary condition, and we also find the Majorana zero modes under the open boundary condition to verify the bulk-edge correspondence.
    Exact surface energy and elementary excitations of the XXX spin-1/2 chain with arbitrary non-diagonal boundary fields
    Jia-Sheng Dong(董家生), Pengcheng Lu(路鹏程), Pei Sun(孙佩), Yi Qiao(乔艺), Junpeng Cao(曹俊鹏), Kun Hao(郝昆), and Wen-Li Yang(杨文力)
    Chin. Phys. B, 2023, 32 (1):  017501.  DOI: 10.1088/1674-1056/ac981f
    Abstract ( 278 )   HTML ( 0 )   PDF (1433KB) ( 106 )  
    We study the physical properties of the XXX spin-1/2 chain with arbitrary non-diagonal boundary fields. By using a combination of numerical analysis and analytical method, we obtain the surface energy and elementary excitations of the model. It shows that the contributions of the two boundary fields to the surface energy are additive. We also find that there exists a kind of excitations related to the boundary string.
    Weak localization in disordered spin-1 chiral fermions
    Shaopeng Miao(苗少鹏), Daifeng Tu(涂岱峰), and Jianhui Zhou(周建辉)
    Chin. Phys. B, 2023, 32 (1):  017502.  DOI: 10.1088/1674-1056/ac720b
    Abstract ( 220 )   HTML ( 2 )   PDF (1782KB) ( 27 )  
    We theoretically investigate the quantum interference theory of magnetotransport of the three-component or spin-1 chiral fermions, which possess two linear Dirac bands and a flat band. For isotropic scalar impurities, the correction of conductivity from the coherent backscatter and non-coherent backscatter contributions cancel out in the intravalley scattering, leading to a weak localization correction to the Drude conductivity from the intervalley scattering. For the anisotropic impurities, the above cancelation is removed, we find the approximative quantum interference conductivity in the weak anisotropy case. The contributions from the chiral anomaly and classical Lorentz force are also discussed. Our work reveals some intriguing and detectable transport signatures of the novel spin-1 chiral fermions.
    Thickness-dependent magnetic properties in Pt/[Co/Ni]n multilayers with perpendicular magnetic anisotropy
    Chunjie Yan(晏春杰), Lina Chen(陈丽娜), Kaiyuan Zhou(周恺元), Liupeng Yang(杨留鹏), Qingwei Fu(付清为), Wenqiang Wang(王文强), Wen-Cheng Yue(岳文诚), Like Liang(梁力克), Zui Tao(陶醉), Jun Du(杜军),Yong-Lei Wang(王永磊), and Ronghua Liu(刘荣华)
    Chin. Phys. B, 2023, 32 (1):  017503.  DOI: 10.1088/1674-1056/ac5c37
    Abstract ( 257 )   HTML ( 0 )   PDF (2060KB) ( 50 )  
    We systematically investigated the Ni and Co thickness-dependent perpendicular magnetic anisotropy (PMA) coefficient, magnetic domain structures, and magnetization dynamics of Pt(5 nm)/[Co($t_{\rm Co}$)/Ni($t_{\rm Ni}$)]$_{5}$/Pt(1 nm) multilayers by combining the four standard magnetic characterization techniques. The magnetic-related hysteresis loops obtained from the field-dependent magnetization $M$ and anomalous Hall resistivity (AHR) $\rho_{{xy}}$ showed that the two serial multilayers with $t_{\rm Co} = 0.2$ nm and 0.3 nm have the optimum PMA coefficient $K_{\rm U}$ as well as the highest coercivity $H_{\rm C}$ at the Ni thickness $t_{\rm Ni}= 0.6 $ nm. Additionally, the magnetic domain structures obtained by magneto-optic Kerr effect (MOKE) microscopy also significantly depend on the thickness and $K_{\rm U}$ of the films. Furthermore, the thickness-dependent linewidth of ferromagnetic resonance is inversely proportional to $K_{\rm U}$ and $H_{\rm C}$, indicating that inhomogeneous magnetic properties dominate the linewidth. However, the intrinsic Gilbert damping constant determined by a linear fitting of the frequency-dependent linewidth does not depend on the Ni thickness and $K_{\rm U}$. Our results could help promote the PMA [Co/Ni] multilayer applications in various spintronic and spin-orbitronic devices.
    Magnetocaloric properties and Griffiths phase of ferrimagnetic cobaltite CaBaCo4O7
    Tina Raoufi, Jincheng He(何金城), Binbin Wang(王彬彬), Enke Liu(刘恩克), and Young Sun(孙阳)
    Chin. Phys. B, 2023, 32 (1):  017504.  DOI: 10.1088/1674-1056/ac8f39
    Abstract ( 274 )   HTML ( 1 )   PDF (1440KB) ( 155 )  
    We present a study on the magnetocaloric properties of a CaBaCo$_{4}$O$_{7}$ polycrystalline cobaltite along with research on the nature of magnetic phase transition. The magnetization as a function of temperature identifies the ferrimagnetic to paramagnetic transition at a Curie temperature of 60 K. Moreover, a Griffiths-like phase is confirmed in a temperature range above $T_{\rm C}$. The compound undergoes a crossover from the first to second-order ferrimagnetic transformation, as evidenced by the Arrott plots, scaling of the universal entropy curve, and field-dependent magnetic entropy change. The maximum of entropy change is 3 J/kg$\cdot$K for $\Delta H = 7$ T at ${T}_{\rm C}$, and a broadening of the entropy peak with increasing magnetic field indicates a field-induced transition above $T_{\rm C}$. The analysis of the magnetic entropy change using the Landau theory reveals the second-order phase transition and indicates that the magnetocaloric properties of CaBaCo$_{4}$O$_{7}$ are dominated by the magnetoelastic coupling and electron interaction. The corresponding values of refrigerant capacity and relative cooling power are estimated to be 33 J/kg and 42 J/kg, respectively.
    Coercivity enhancement of sintered Nd-Fe-B magnets by grain boundary diffusion with Pr80-xAlxCu20 alloys
    Zhe-Huan Jin(金哲欢), Lei Jin(金磊), Guang-Fei Ding(丁广飞), Shuai Guo(郭帅), Bo Zheng(郑波),Si-Ning Fan(樊思宁), Zhi-Xiang Wang(王志翔), Xiao-Dong Fan(范晓东), Jin-Hao Zhu(朱金豪),Ren-Jie Chen(陈仁杰), A-Ru Yan(闫阿儒), Jing Pan(潘晶), and Xin-Cai Liu(刘新才)
    Chin. Phys. B, 2023, 32 (1):  017505.  DOI: 10.1088/1674-1056/ac6741
    Abstract ( 269 )   HTML ( 0 )   PDF (6788KB) ( 130 )  
    A grain boundary diffusion (GBD) process with Pr80-xAlxCu20 (x = 0, 10, 15, 20) low melting point alloys was applied to commercial 42M sintered Nd-Fe-B magnets. The best coercivity enhancement of a diffused magnet was for the Pr65Al15Cu20 GBD magnet, from 16.38 kOe to 22.38 kOe. Microstructural investigations indicated that increase in the Al content in the diffusion source can form a continuous grain boundary (GB) phase, optimizing the microstructure to enhance the coercivity. The coercivity enhancement is mainly due to the formation of a continuous GB phase to separate the main phase grains. Exchange decoupling between the adjacent main phase grains is enhanced after the GBD process. Meanwhile, the introduction of Al can effectively promote the infiltration of Pr into the magnet, which increases the diffusion rate of rare-earth elements within a certain range. This work provides a feasible method to enhance coercivity and reduce the use of rare-earth resources by partial replacement of rare-earth elements with non-rare-earth elements in the diffusion source.
    Skyrmion-based logic gates controlled by electric currents in synthetic antiferromagnet
    Linlin Li(李林霖), Jia Luo(罗佳), Jing Xia(夏静), Yan Zhou(周艳), Xiaoxi Liu(刘小晰), and Guoping Zhao(赵国平)
    Chin. Phys. B, 2023, 32 (1):  017506.  DOI: 10.1088/1674-1056/ac9b01
    Abstract ( 340 )   HTML ( 0 )   PDF (1897KB) ( 127 )  
    Skyrmions in synthetic antiferromagnetic (SAF) systems have attracted much attention in recent years due to their superior stability, high-speed mobility, and completely compensated skyrmion Hall effect. They are promising building blocks for the next generation of magnetic storage and computing devices with ultra-low energy and ultra-high density. Here, we theoretically investigate the motion of a skyrmion in an SAF bilayer racetrack and find the velocity of a skyrmion can be controlled jointly by the edge effect and the driving force induced by the spin current. Furthermore, we propose a logic gate that can realize different logic functions of logic AND, OR, NOT, NAND, NOR, and XOR gates. Several effects including the spin-orbit torque, the skyrmion Hall effect, skyrmion-skyrmion repulsion, and skyrmion-edge interaction are considered in this design. Our work may provide a way to utilize the SAF skyrmion as a versatile information carrier for future energy-efficient logic gates.
    Prediction of flexoelectricity in BaTiO3 using molecular dynamics simulations
    Long Zhou(周龙), Xu-Long Zhang(张旭龙), Yu-Ying Cao(曹玉莹), Fu Zheng(郑富), Hua Gao(高华), Hong-Fei Liu(刘红飞), and Zhi Ma(马治)
    Chin. Phys. B, 2023, 32 (1):  017701.  DOI: 10.1088/1674-1056/ac70be
    Abstract ( 270 )   HTML ( 1 )   PDF (1368KB) ( 163 )  
    Flexoelectric effect, referring to the strain gradient induced polarization, widely exists in dielectric materials, but its molecular dynamics has not been studied so much so far. In this work, the radial distribution function of BaTiO3 and the phase transition temperatures have been investigated, and the results show that the core-shell potential model is effective and the structure of BaTiO3 is stable in a temperature range of 10 K-150 K. Molecular dynamics simulated hysteresis loops of BaTiO3 show that anisotropy can play an important role in the coercive field. Based on the rational simulation process, the effects of cantilever beam bent angle and fixed length on the polarization are analyzed. It is found that the small bent angle of the curved cantilever beam can give a proportional relationship with a fixed end length and a non-linear relationship is presented when the bent angle is much larger. The prediction of flexoelectric coefficient in BaTiO3 is 18.5 nC/m. This work provides a computational framework for the study of flexoelectric effect by using molecular dynamics.
    Electroluminescence explored internal behavior of carriers in InGaAsP single-junction solar cell
    Xue-Fei Li(李雪飞), Wen-Xian Yang(杨文献), Jun-Hua Long(龙军华), Ming Tan(谭明), Shan Jin(金山), Dong-Ying Wu(吴栋颖), Yuan-Yuan Wu(吴渊渊), and Shu-Long Lu(陆书龙)
    Chin. Phys. B, 2023, 32 (1):  017801.  DOI: 10.1088/1674-1056/ac7448
    Abstract ( 210 )   HTML ( 0 )   PDF (614KB) ( 50 )  
    The internal behaviors of carriers in InGaAsP single-junction solar cell are investigated by using electroluminescence (EL) measurements. Two emission peaks can be observed in current-dependent electroluminescence spectra at low temperatures, and carrier localization exists for both peaks under low excitation. The trends of power index α extracted from excitation-dependent EL spectra at different temperatures imply that there exists a competition between Shockley-Read-Hall recombination and Auger recombination. Auger recombination becomes dominant at high temperatures, which is probably responsible for the lower current density of InGaAsP solar cell. Besides, the anomalous "S-shape" tendency with the temperature of band-edge peak position can be attributed to potential fluctuation and carrier redistribution, demonstrating delocalization, transfer, and redistribution of carriers in the continuum band-edge. Furthermore, the strong reduction of activation energy at high excitations indicates that electrons and holes escaped independently, and the faster-escaping carriers are holes.
    Method of measuring one-dimensional photonic crystal period-structure-film thickness based on Bloch surface wave enhanced Goos-Hänchen shift
    Yao-Pu Lang(郎垚璞), Qing-Gang Liu(刘庆纲), Qi Wang(王奇), Xing-Lin Zhou(周兴林), and Guang-Yi Jia(贾光一)
    Chin. Phys. B, 2023, 32 (1):  017802.  DOI: 10.1088/1674-1056/ac6b24
    Abstract ( 241 )   HTML ( 1 )   PDF (2063KB) ( 93 )  
    This paper puts forward a novel method of measuring the thin period-structure-film thickness based on the Bloch surface wave (BSW) enhanced Goos-Hänchen (GH) shift in one-dimensional photonic crystal (1DPC). The BSW phenomenon appearing in 1DPC enhances the GH shift generated in the attenuated total internal reflection structure. The GH shift is closely related to the thickness of the film which is composed of layer-structure of 1DPC. The GH shifts under multiple different incident light conditions will be obtained by varying the wavelength and angle of the measured light, and the thickness distribution of the entire structure of 1DPC is calculated by the particle swarm optimization (PSO) algorithm. The relationship between the structure of a 1DPC film composed of TiO2 and SiO2 layers and the GH shift, is investigated. Under the specific photonic crystal structure and incident conditions, a giant GH shift, 5.1×103 times the wavelength of incidence, can be obtained theoretically. Simulation and calculation results show that the thickness of termination layer and periodic structure bilayer of 1DPC film with 0.1-nm resolution can be obtained by measuring the GH shifts. The exact structure of a 1DPC film is innovatively measured by the BSW-enhanced GH shift.
    Growth behaviors and emission properties of Co-deposited MAPbI3 ultrathin films on MoS2
    Siwen You(游思雯), Ziyi Shao(邵子依), Xiao Guo(郭晓), Junjie Jiang(蒋俊杰), Jinxin Liu(刘金鑫), Kai Wang(王凯), Mingjun Li(李明君), Fangping Ouyang(欧阳方平), Chuyun Deng(邓楚芸), Fei Song(宋飞), Jiatao Sun(孙家涛), and Han Huang(黄寒)
    Chin. Phys. B, 2023, 32 (1):  017901.  DOI: 10.1088/1674-1056/ac8e9b
    Abstract ( 238 )   HTML ( 0 )   PDF (1771KB) ( 79 )  
    Hybrid organic-inorganic perovskite thin films have attracted much attention in optoelectronic and information fields because of their intriguing properties. Due to quantum confinement effects, ultrathin films in nm scale usually show special properties. Here, we report on the growth of methylammonium lead iodide (MAPbI3) ultrathin films via co-deposition of PbI2 and CH3NH3I (MAI) on chemical-vapor-deposition-grown monolayer MoS2 as well as the corresponding photoluminescence (PL) properties at different growing stages. Atomic force microscopy and scanning electron microscopy measurements reveal the MoS2 tuned growth of MAPbI3 in a Stranski-Krastanov mode. PL and Kelvin probe force microscopy results confirm that MAPbI3/MoS2 heterostructures have a type-II energy level alignment at the interface. Temperaturedependent PL measurements on layered MAPbI3 (at the initial stage) and on MAPbI3 crystals in averaged size of 500 nm (at the later stage) show rather different temperature dependence as well as the phase transitions from tetragonal to orthorhombic at 120 and 150 K, respectively. Our findings are useful in fabricating MAPbI3/transition-metal dichalcogenide based innovative devices for wider optoelectronic applications.
    Optical and electrical properties of BaSnO3 and In2O3 mixed transparent conductive films deposited by filtered cathodic vacuum arc technique at room temperature
    Jian-Ke Yao(姚建可) and Wen-Sen Zhong(钟文森)
    Chin. Phys. B, 2023, 32 (1):  018101.  DOI: 10.1088/1674-1056/ac8ce7
    Abstract ( 244 )   HTML ( 0 )   PDF (1205KB) ( 102 )  
    For the crystalline temperature of BaSnO$_{3}$ (BTO) was above 650 ℃, the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process. In the article, the microstructure, optical and electrical of BTO and In$_{2}$O$_{3}$ mixed transparent conductive BaInSnO$_x$ (BITO) film deposited by filtered cathodic vacuum arc technique (FCVA) on glass substrate at room temperature were firstly reported. The BITO film with thickness of 300 nm had mainly In$_{2}$O$_{3}$ polycrystalline phase, and minor polycrystalline BTO phase with (001), (011), (111), (002), (222) crystal faces which were first deposited at room temperature on amorphous glass. The transmittance was 70%-80% in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550-nm wavelength. The basic optical properties included the real and imaginary parts, high frequency dielectric constants, the absorption coefficient, the Urbach energy, the indirect and direct band gaps, the oscillator and dispersion energies, the static refractive index and dielectric constant, the average oscillator wavelength, oscillator length strength, the linear and the third-order nonlinear optical susceptibilities, and the nonlinear refractive index were all calculated. The film was the n-type conductor with sheet resistance of 704.7 $\Omega /\Box $, resistivity of 0.02 $\Omega \cdot$cm, mobility of 18.9 cm$^{2}$/V$\cdot$s, and carrier electron concentration of $1.6\times 10^{19}$ cm$^{-3}$ at room temperature. The results suggested that the BITO film deposited by FCVA had potential application in transparent conductive films-based low temperature device process.
    A new transition metal diphosphide α-MoP2 synthesized by a high-temperature and high-pressure technique
    Xiaolei Liu(刘晓磊), Zhenhai Yu(于振海), Jianfu Li(李建福), Zhenzhen Xu(徐真真), Chunyin Zhou(周春银), Zhaohui Dong(董朝辉), Lili Zhang(张丽丽), Xia Wang(王霞), Na Yu(余娜), Zhiqiang Zou(邹志强),Xiaoli Wang(王晓丽), and Yanfeng Guo(郭艳峰)
    Chin. Phys. B, 2023, 32 (1):  018102.  DOI: 10.1088/1674-1056/ac633d
    Abstract ( 233 )   HTML ( 2 )   PDF (1268KB) ( 86 )  
    Monoclinic $\alpha $-MoP$_{2}$, with the OsGe$_{2}$-type structure (space group $C2/m$, $Z = 4$) and lattice parameters $a = 8.7248(11) $ Å, $b = 3.2322(4) $ Å, $c = 7.4724(9) $ Å, and $\beta =119.263^\circ $, was synthesized under a pressure of 4 GPa at a temperature between 1100 ${^\circ}$C and 1200 ${^\circ}$C. The structure of $\alpha $-MoP$_{2}$ and its relationship to other transition metal diphosphides are discussed. Surprisingly, the ambient pressure phase orthorhombic $\beta $-MoP$_{2}$ (space group Cmc2$_{1}$) is denser in structure than $\alpha $-MoP$_{2}$. Room-temperature high-pressure x-ray diffraction studies exclude the possibility of phase transition from $\beta $-MoP$_{2}$ to $\alpha $-MoP$_{2}$, suggesting that $\alpha $-MoP$_{2}$ is a stable phase at ambient conditions; this is also supported by the total energy and phonon calculations.
    High throughput N-modular redundancy for error correction design of memristive stateful logic
    Xi Zhu(朱熙), Hui Xu(徐晖), Weiping Yang(杨为平), Zhiwei Li(李智炜), Haijun Liu(刘海军), Sen Liu(刘森), Yinan Wang(王义楠), and Hongchang Long(龙泓昌)
    Chin. Phys. B, 2023, 32 (1):  018502.  DOI: 10.1088/1674-1056/ac8f38
    Abstract ( 274 )   HTML ( 0 )   PDF (6363KB) ( 86 )  
    Memristive stateful logic is one of the most promising candidates to implement an in-memory computing system that computes within the storage unit. It can eliminate the costs for the data movement in the traditional von Neumann system. However, the instability in the memristors is inevitable due to the limitation of the current fabrication technology, which incurs a great challenge for the reliability of the memristive stateful logic. In this paper, the implication of device instability on the reliability of the logic event is simulated. The mathematical relationship between logic reliability and redundancy has been deduced. By combining the mathematical relationship with the vector-matrix multiplication in a memristive crossbar array, the logic error correction scheme with high throughput has been proposed. Moreover, a universal design paradigm has been put forward for complex logic. And the circuit schematic and the flow of the scheme have been raised. Finally, a 1-bit full adder (FA) based on the NOR logic and NOT logic is simulated and the mathematical evaluation is performed. It demonstrates the scheme can improve the reliability of the logic significantly. And compared with other four error corrections, the scheme which can be suitable for all kinds of R-R logics and V-R logics has the best universality and throughput. Compared with the other two approaches which also need additional complementary metal-oxide semiconductor (CMOS) circuits, it needs fewer transistors and cycles for the error correction.
    High-performance amorphous In-Ga-Zn-O thin-film transistor nonvolatile memory with a novel p-SnO/n-SnO2 heterojunction charge trapping stack
    Wen Xiong(熊文), Jing-Yong Huo(霍景永), Xiao-Han Wu(吴小晗), Wen-Jun Liu(刘文军),David Wei Zhang(张卫), and Shi-Jin Ding(丁士进)
    Chin. Phys. B, 2023, 32 (1):  018503.  DOI: 10.1088/1674-1056/ac6dbf
    Abstract ( 218 )   HTML ( 1 )   PDF (1005KB) ( 55 )  
    Amorphous In-Ga-Zn-O (a-IGZO) thin-film transistor (TFT) memories with novel p-SnO/n-SnO2 heterojunction charge trapping stacks (CTSs) are investigated comparatively under a maximum fabrication temperature of 280 ℃. Compared to a single p-SnO or n-SnO2 charge trapping layer (CTL), the heterojunction CTSs can achieve electrically programmable and erasable characteristics as well as good data retention. Of the two CTSs, the tunneling layer/p-SnO/n-SnO2/blocking layer architecture demonstrates much higher program efficiency, more robust data retention, and comparably superior erase characteristics. The resulting memory window is as large as 6.66 V after programming at 13 V/1 ms and erasing at -8 V/1 ms, and the ten-year memory window is extrapolated to be 4.41 V. This is attributed to shallow traps in p-SnO and deep traps in n-SnO2, and the formation of a built-in electric field in the heterojunction.
    A self-driven photodetector based on a SnS2/WS2 van der Waals heterojunction with an Al2O3 capping layer
    Hsiang-Chun Wang(王祥骏), Yuheng Lin(林钰恒), Xiao Liu(刘潇), Xuanhua Deng(邓煊华),Jianwei Ben(贲建伟), Wenjie Yu(俞文杰), Deliang Zhu(朱德亮), and Xinke Liu(刘新科)
    Chin. Phys. B, 2023, 32 (1):  018504.  DOI: 10.1088/1674-1056/ac6dbd
    Abstract ( 279 )   HTML ( 1 )   PDF (827KB) ( 73 )  
    Photodetectors based on two-dimensional (2D) materials have attracted considerable attention because of their unique properties. To further improve the performance of self-driven photodetectors based on van der Waals heterojunctions, a conductive band minimum (CBM) matched self-driven SnS2/WS2 van der Waals heterojunction photodetector based on a SiO2/Si substrate has been designed. The device exhibits a positive current at zero voltage under 365 nm laser illumination. This is attributed to the built-in electric field at the interface of the SnS2 and WS2 layer, which will separate and transport the photogenerated carriers, even at zero bias voltage. In addition, the Al2O3 layer is covered by the surface of the SnS2/WS2 photodetector to further improve the performance, because the Al2O3 layer will introduce tensile stress on the surface of the 2D materials leading to a higher electron concentration and smaller effective mass of electrons in the films. This work provides an idea for the research of self-driven photodetectors based on a van der Waals heterogeneous junction.
    A field-effect WSe2/Si heterojunction diode
    Rui Yu(余睿), Zhe Sheng(盛喆), Wennan Hu(胡文楠), Yue Wang(王越), Jianguo Dong(董建国), Haoran Sun(孙浩然), Zengguang Cheng(程增光), and Zengxing Zhang(张增星)
    Chin. Phys. B, 2023, 32 (1):  018505.  DOI: 10.1088/1674-1056/ac9049
    Abstract ( 248 )   HTML ( 1 )   PDF (1074KB) ( 125 )  
    It is significant to develop a heterogeneous integration technology to promote the application of two-dimensional (2D) materials in silicon roadmap. In this paper, we reported a field-effect WSe2/Si heterojunction diode based on ambipolar 2D WSe2 and silicon on insulator (SOI). Our results indicate that the device exhibits a p-n diode behavior with a rectifying ratio of ~ 300 and an ideality factor of 1.37. As a photodetector, it has optoelectronic properties with a response time of 0.13 ms, responsivity of 0.045 A/W, detectivity of 4.5×1010 Jones and external quantum efficiency (EQE) of 8.9 %. Due to the ambipolar behavior of the WSe2, the rectifying and optoelectronic properties of the heterojunction diode can be modulated by the gate electrical field, enabling various potential applications such as logic optoelectronic devices and neuromorphic optoelectronic devices for in-sensor computing circuits. Thanks to the process based on the mature SOI technique, our field-effect heterojunction diode should have obvious advantages in device isolation and integration.
    Adsorption dynamics of double-stranded DNA on a graphene oxide surface with both large unoxidized and oxidized regions
    Mengjiao Wu(吴梦娇), Huishu Ma(马慧姝), Haiping Fang(方海平), Li Yang(阳丽), and Xiaoling Lei(雷晓玲)
    Chin. Phys. B, 2023, 32 (1):  018701.  DOI: 10.1088/1674-1056/ac5c3a
    Abstract ( 234 )   HTML ( 0 )   PDF (1343KB) ( 107 )  
    The adsorption dynamics of double-stranded DNA (dsDNA) molecules on a graphene oxide (GO) surface are important for applications of DNA/GO functional structures in biosensors, biomedicine and materials science. In this work, molecular dynamics simulations were used to examine the adsorption of different length dsDNA molecules (from 4 bp to 24 bp) on the GO surface. The dsDNA molecules could be adsorbed on the GO surface through the terminal bases and stand on the GO surface. For short dsDNA (4 bp) molecules, the double-helix structure was partially or totally broken and the adsorption dynamics was affected by the structural fluctuation of short dsDNA and the distribution of the oxidized groups on the GO surface. For long dsDNA molecules (from 8 bp to 24 bp) adsorption is stable. By nonlinear fitting of the contact angle between the axis of the dsDNA molecule and the GO surface, we found that a dsDNA molecule adsorbed on a GO surface has the chance of orienting parallel to the GO surface if the length of the dsDNA molecule is longer than 54 bp. We attributed this behavior to the flexibility of dsDNA molecules. With increasing length, the flexibility of dsDNA molecules also increases, and this increasing flexibility gives an adsorbed dsDNA molecule more chance of reaching the GO surface with the free terminal. This work provides a whole picture of adsorption of dsDNA molecules on the GO surface and should be of benefit for the design of DNA/GO based biosensors.
    Chiral lateral optical force near plasmonic ring induced by Laguerre-Gaussian beam
    Ying-Dong Nie(聂英东), Zhi-Guang Sun(孙智广), and Yu-Rui Fang(方蔚瑞)
    Chin. Phys. B, 2023, 32 (1):  018702.  DOI: 10.1088/1674-1056/ac6eea
    Abstract ( 245 )   HTML ( 0 )   PDF (2239KB) ( 95 )  
    Owing to the good adjustability and the strong near-field enhancement, surface plasmons are widely used in optical force trap, thus the optical force trap can achieve excellent performance. Here, we use the Laguerre-Gaussian beam and a plasmonic gold ring to separate enantiomers by the chiral optical force. Along with the radial optical force that traps the particles, there is also a chirality-sign-sensitive lateral force arising from the optical spin angular momentum, which is caused by the interaction between optical orbit angular momentum and gold ring structure. By selecting a specific incident wavelength, the strong angular scattering and non-chiral related azimuthal optical force can be suppressed. Thus the chiral related azimuthal optical force can induce an opposite orbital rotation of the trapped particles with chirality of different sign near the gold ring. This work proposes an effective approach for catchingand separating chiral enantiomers.
    Effect of a static pedestrian as an exit obstacle on evacuation
    Yang-Hui Hu(胡杨慧), Yu-Bo Bi(毕钰帛), Jun Zhang(张俊), Li-Ping Lian(练丽萍), Wei-Guo Song(宋卫国), and Wei Gao(高伟)
    Chin. Phys. B, 2023, 32 (1):  018901.  DOI: 10.1088/1674-1056/ac9605
    Abstract ( 317 )   HTML ( 0 )   PDF (2788KB) ( 140 )  
    Building exit as a bottleneck structure is the last and the most congested stage in building evacuation. It is well known that obstacles at the exit affect the evacuation process, but few researchers pay attention to the effect of stationary pedestrians (the elderly with slow speed, the injured, and the static evacuation guide) as obstacles at the exit on the evacuation process. This paper explores the influence of the presence of a stationary pedestrian as an obstacle at the exit on the evacuation from experiments and simulations. We use a software, Pathfinder, based on the agent-based model to study the effect of ratios of exit width ($D$) to distance ($d$) between the static pedestrian and the exit, the asymmetric structure by shifting the static pedestrian upward, and types of obstacles on evacuation. Results show that the evacuation time of scenes with a static pedestrian is longer than that of scenes with an obstacle due to the unexpected hindering effect of the static pedestrian. Different ratios of $D/d$ have different effects on evacuation efficiency. Among the five $D/d$ ratios in this paper, the evacuation efficiency is the largest when $d$ is equal to $0.75D$, and the existence of the static pedestrian has a positive impact on evacuation in this condition. The influence of the asymmetric structure of the static pedestrian on evacuation efficiency is affected by $D/d$. This study can provide a theoretical basis for crowd management and evacuation plan near the exit of complex buildings and facilities.
    A novel lattice model integrating the cooperative deviation of density and optimal flux under V2X environment
    Guang-Han Peng(彭光含), Chun-Li Luo(罗春莉), Hong-Zhuan Zhao(赵红专), and Hui-Li Tan(谭惠丽)
    Chin. Phys. B, 2023, 32 (1):  018902.  DOI: 10.1088/1674-1056/ac65f1
    Abstract ( 243 )   HTML ( 3 )   PDF (862KB) ( 44 )  
    A novel lattice hydrodynamic model is proposed by integrating the cooperative deviation of density and optimal flux under vehicle to X (V2X) environment. According to the theoretical analysis, the stability conditions and the mKdV equations affected by the cooperative deviation of traffic information are explored. And the density wave, hysteresis loop and energy consumption of the traffic flow have been investigated via numerical simulation. The results indicate that the cooperative deviation of density and optimal flux can effectively alleviate the traffic congestion. More importantly, our new consideration can reduce fuel consumption and exhaust emission under the V2X environment.
    Vertex centrality of complex networks based on joint nonnegative matrix factorization and graph embedding
    Pengli Lu(卢鹏丽) and Wei Chen(陈玮)
    Chin. Phys. B, 2023, 32 (1):  018903.  DOI: 10.1088/1674-1056/ac6867
    Abstract ( 215 )   HTML ( 0 )   PDF (1970KB) ( 62 )  
    Finding crucial vertices is a key problem for improving the reliability and ensuring the effective operation of networks, solved by approaches based on multiple attribute decision that suffer from ignoring the correlation among each attribute or the heterogeneity between attribute and structure. To overcome these problems, a novel vertex centrality approach, called VCJG, is proposed based on joint nonnegative matrix factorization and graph embedding. The potential attributes with linearly independent and the structure information are captured automatically in light of nonnegative matrix factorization for factorizing the weighted adjacent matrix and the structure matrix, which is generated by graph embedding. And the smoothness strategy is applied to eliminate the heterogeneity between attributes and structure by joint nonnegative matrix factorization. Then VCJG integrates the above steps to formulate an overall objective function, and obtain the ultimately potential attributes fused the structure information of network through optimizing the objective function. Finally, the attributes are combined with neighborhood rules to evaluate vertex's importance. Through comparative analyses with experiments on nine real-world networks, we demonstrate that the proposed approach outperforms nine state-of-the-art algorithms for identification of vital vertices with respect to correlation, monotonicity and accuracy of top-10 vertices ranking.
ISSN 1674-1056   CN 11-5639/O4
, Vol. 32, No. 1

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