Content of in our journal

        Published in last 1 year |  In last 2 years |  In last 3 years |  All
    Please wait a minute...
    For selected: Toggle thumbnails
    Ultrafast Coulomb explosion imaging of molecules and molecular clusters
    Xiaokai Li(李孝开), Xitao Yu(余西涛), Pan Ma(马盼), Xinning Zhao(赵欣宁), Chuncheng Wang(王春成), Sizuo Luo(罗嗣佐), and Dajun Ding(丁大军)
    Chin. Phys. B, 2022, 31 (10): 103304.   DOI: 10.1088/1674-1056/ac89df
    Abstract242)   HTML4)    PDF (8816KB)(184)      
    Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging (CEI) provides a great opportunity to make this dream a reality for small molecules or their aggregation —— clusters. The method is unique for identifying the atomic locations with ångstrom spatial resolution and capturing the structural evolution with a femtosecond time scale, in particular for imaging transient state products. This review summarizes the determination of three-dimensional equilibrium geometry of molecules and molecular cluster system through the reconstruction from the fragments momenta, and also shows that the dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast CEI (UCEI). Furthermore, the detailed measurement and analysis procedures of the CEI, theoretical methods, exemplary results, and future perspectives of the technique are described.
    Magnetic van der Waals materials: Synthesis, structure, magnetism, and their potential applications
    Zhongchong Lin(林中冲), Yuxuan Peng(彭宇轩), Baochun Wu(吴葆春), Changsheng Wang(王常生), Zhaochu Luo(罗昭初), and Jinbo Yang(杨金波)
    Chin. Phys. B, 2022, 31 (8): 087506.   DOI: 10.1088/1674-1056/ac6eed
    Abstract306)   HTML6)    PDF (2684KB)(374)      
    As the family of magnetic materials is rapidly growing, two-dimensional (2D) van der Waals (vdW) magnets have attracted increasing attention as a platform to explore fundamental physical problems of magnetism and their potential applications. This paper reviews the recent progress on emergent vdW magnetic compounds and their potential applications in devices. First, we summarize the current vdW magnetic materials and their synthetic methods. Then, we focus on their structure and the modulation of magnetic properties by analyzing the representative vdW magnetic materials with different magnetic structures. In addition, we pay attention to the heterostructures of vdW magnetic materials, which are expected to produce revolutionary applications of magnetism-related devices. To motivate the researchers in this area, we finally provide the challenges and outlook on 2D vdW magnetism.
    Erratum to “Boundary layer flow and heat transfer of a Casson fluid past a symmetric porous wedge with surface heat flux”
    Swati Mukhopadhyay and Iswar Chandra Mandal
    Chin. Phys. B, 2022, 31 (5): 059902.   DOI: 10.1088/1674-1056/ac67c8
    Abstract246)   HTML0)    PDF (721KB)(28)      
    We would like to acknowledge the misprinted terms in our published paper “Boundary layer flow and heat transfer of a Casson fluid past a symmetric porous wedge with surface heat flux” [Chin. Phys. B 23 044702 (2014)]. Since only two misprints exist and the main results of the published paper are correct, we present the correct equations in this erratum.
    Observation of magnetoresistance in CrI3/graphene van der Waals heterostructures
    Yu-Ting Niu(牛宇婷), Xiao Lu(鲁晓), Zhong-Tai Shi(石钟太), and Bo Peng(彭波)
    Chin. Phys. B, 2021, 30 (11): 117506.   DOI: 10.1088/1674-1056/ac1e1d
    Abstract466)   HTML8)    PDF (1106KB)(266)      
    Two-dimensional ferromagnetic van der Waals (2D vdW) heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic layered materials, and for manipulating spin degree of freedom at the limit of few atomic layers, which empower next-generation spintronic and memory devices. However, to date, the electronic properties of 2D ferromagnetic heterostructures still remain elusive. Here, we report an unambiguous magnetoresistance behavior in CrI3/graphene heterostructures, with a maximum magnetoresistance ratio of 2.8%. The magnetoresistance increases with increasing magnetic field, which leads to decreasing carrier densities through Lorentz force, and decreases with the increase of the bias voltage. This work highlights the feasibilities of applying two-dimensional ferromagnetic vdW heterostructures in spintronic and memory devices.
    Phase-sensitive Landau-Zener-Stückelberg interference in superconducting quantum circuit
    Zhi-Xuan Yang(杨智璇), Yi-Meng Zhang(张一萌), Yu-Xuan Zhou(周宇轩), Li-Bo Zhang(张礼博), Fei Yan(燕飞), Song Liu(刘松), Yuan Xu(徐源), and Jian Li(李剑)
    Chin. Phys. B, 2021, 30 (2): 024212.   DOI: 10.1088/1674-1056/abd753
    Abstract631)   HTML4)    PDF (1157KB)(194)      
    Superconducting circuit quantum electrodynamics (QED) architecture composed of superconducting qubit and resonator is a powerful platform for exploring quantum physics and quantum information processing. By employing techniques developed for superconducting quantum computing, we experimentally investigate phase-sensitive Landau-Zener-Stückelberg (LZS) interference phenomena in a circuit QED. Our experiments cover an extensive range of LZS transition parameters and demonstrate the LZS induced Rabi-like oscillation as well as phase-dependent steady-state population.
    Quench dynamics in 1D model with 3rd-nearest-neighbor hoppings
    Shuai Yue(岳帅), Xiang-Fa Zhou(周祥发), and Zheng-Wei Zhou(周正威)
    Chin. Phys. B, 2021, 30 (2): 026402.   DOI: 10.1088/1674-1056/abd742
    Abstract470)   HTML4)    PDF (1731KB)(146)      
    The non-equilibrium dynamics of a one-dimensional (1D) topological system with 3rd-nearest-neighbor hopping has been investigated by analytical and numerical methods. An analytical form of topological defect density under the periodic boundary conditions (PBC) is obtained by using the Landau-Zener formula (LZF), which is consistent with the scaling of defect production provided by the Kibble-Zurek mechanism (KZM). Under the open boundary conditions (OBC), quench dynamics becomes more complicated due to edge states. The behaviors of the system quenching across different phases show that defect production no longer satisfies the KZM paradigm since complicated couplings exist under OBC. Some new dynamical features are revealed.
    Lattice thermal conductivity of β12 and χ3 borophene
    Jia He(何佳), Yulou Ouyang(欧阳宇楼), Cuiqian Yu(俞崔前), Pengfei Jiang(蒋鹏飞), Weijun Ren(任卫君), and Jie Chen(陈杰)
    Chin. Phys. B, 2020, 29 (12): 126503.   DOI: 10.1088/1674-1056/abbbe6
    Abstract459)   HTML    PDF (3830KB)(235)      
    Borophene allotropes have many unique physical properties due to their polymorphism and similarity between boron and carbon. In this work, based on the density functional theory and phonon Boltzmann transport equation, we investigate the lattice thermal conductivity $\kappa $ of both β 12 and χ3 borophene. Interestingly, these two allotropes with similar lattice structures have completely different thermal transport properties. β12 borophene has almost isotropic $\kappa $ around 90 W/(mK) at 300 K, while $\kappa $ of χ3 borophene is much larger and highly anisotropic. The room temperature $\kappa $ of χ 3 borophene along the armchair direction is 512 W/(mK), which is comparable to that of hexagonal boron nitride but much higher than most of the two-dimensional materials. The physical mechanisms responsible for such distinct thermal transport behavior are discussed based on the spectral phonon analysis. More interestingly, we uncover a unique one-dimensional transport feature of transverse acoustic phonon in χ3 borophene along the armchair direction, which results in a boost of phonon relaxation time and thus leads to the significant anisotropy and ultrahigh thermal conductivity in χ3 borophene. Our study suggests that χ 3 borophene may have promising application in heat dissipation, and also provides novel insights for enhancing the thermal transport in two-dimensional systems.
    Machine learning identification of impurities in the STM images
    Ce Wang(王策), Haiwei Li(李海威), Zhenqi Hao(郝镇齐), Xintong Li(李昕彤), Changwei Zou(邹昌炜), Peng Cai(蔡鹏), Yayu Wang(王亚愚), Yi-Zhuang You(尤亦庄), and Hui Zhai(翟荟)
    Chin. Phys. B, 2020, 29 (11): 116805.   DOI: 10.1088/1674-1056/abc0d5
    Abstract615)   HTML    PDF (1270KB)(318)      

    We train a neural network to identify impurities in the experimental images obtained by the scanning tunneling microscope (STM) measurements. The neural network is first trained with a large number of simulated data and then the trained neural network is applied to identify a set of experimental images taken at different voltages. We use the convolutional neural network to extract features from the images and also implement the attention mechanism to capture the correlations between images taken at different voltages. We note that the simulated data can capture the universal Friedel oscillation but cannot properly describe the non-universal physics short-range physics nearby an impurity, as well as noises in the experimental data. And we emphasize that the key of this approach is to properly deal with these differences between simulated data and experimental data. Here we show that even by including uncorrelated white noises in the simulated data, the performance of the neural network on experimental data can be significantly improved. To prevent the neural network from learning unphysical short-range physics, we also develop another method to evaluate the confidence of the neural network prediction on experimental data and to add this confidence measure into the loss function. We show that adding such an extra loss function can also improve the performance on experimental data. Our research can inspire future similar applications of machine learning on experimental data analysis.

    Computational screening of doping schemes for LiTi2(PO4)3 as cathode coating materials
    Yu-Qi Wang(王宇琦), Xiao-Rui Sun(孙晓瑞), Rui-Juan Xiao(肖睿娟), Li-Quan Chen(陈立泉)
    Chin. Phys. B, 2020, 29 (3): 038202.   DOI: 10.1088/1674-1056/ab7186
    Abstract661)   HTML    PDF (1030KB)(303)      
    In all-solid-state lithium batteries, the impedance at the cathode/electrolyte interface shows close relationship with the cycle performance. Cathode coatings are helpful to reduce the impedance and increase the stability at the interface effectively. LiTi2(PO4)3 (LTP), a fast ion conductor with high ionic conductivity approaching 10-3 S·cm-1, is adopted as the coating materials in this study. The crystal and electronic structures, as well as the Li+ ion migration properties are evaluated for LTP and its doped derivatives based on density functional theory (DFT) and bond valence (BV) method. Substituting part of Ti sites with element Mn, Fe, or Mg in LTP can improve the electronic conductivity of LTP while does not decrease its high ionic conductivity. In this way, the coating materials with both high ionic conductivities and electronic conductivities can be prepared for all-solid-state lithium batteries to improve the ion and electron transport properties at the interface.
    In vivo hyperthermia effect induced by high
    TU Juan (屠娟)
    Chin. Phys. B,
    A method for extracting human gait series from accelerometer signals based on the ensemble empirical mode decomposition
    Fu Mao-Jing(符懋敬), Zhuang Jian-Jun(庄建军), Hou Feng-Zhen(侯凤贞), Zhan Qing-Bo(展庆波),Shao Yi(邵毅), and Ning Xin-Bao(宁新宝)
    Chin. Phys. B, 2010, 19 (5): 058701.   DOI: 10.1088/1674-1056/19/5/058701
    Abstract892)      PDF (1137KB)(254)      
    In this paper, the ensemble empirical mode decomposition (EEMD) is applied to analyse accelerometer signals collected during human normal walking. First, the self-adaptive feature of EEMD is utilised to decompose the accelerometer signals, thus sifting out several intrinsic mode functions (IMFs) at disparate scales. Then, gait series can be extracted through peak detection from the eigen IMF that best represents gait rhythmicity. Compared with the method based on the empirical mode decomposition (EMD), the EEMD-based method has following advantages: it remarkably improves the detection rate of peak values hidden in the original accelerometer signal, even when the signal is severely contaminated by the intermittent noises; this method effectively prevents the phenomenon of mode mixing found in the process of EMD. And a reasonable selection of parameters for the stop-filtering criteria can improve the calculation speed of the EEMD-based method. Meanwhile, the endpoint effect can be suppressed by using the auto regressive and moving average model to extend a short-time series in dual directions. The results suggest that EEMD is a powerful tool for extraction of gait rhythmicity and it also provides valuable clues for extracting eigen rhythm of other physiological signals.
    Periodic-cylinder vesicle with minimal energy
    Zhou Xiao-Hua(周晓华)
    Chin. Phys. B, 2010, 19 (5): 058702.   DOI: 10.1088/1674-1056/19/5/058702
    Abstract1009)      PDF (129KB)(420)