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CN 11-5639/O4
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Formation of unusual Cr5+ charge state in CaCr0.5Fe0.5O3 perovskite Hot!

Jian-Hong Dai(戴建洪), Qing Zhao(赵庆), Qian Sun(孙倩), Shuo Zhang(张硕), Xiao Wang(王潇), Xu-Dong Shen(申旭东), Zhe-Hong Liu(刘哲宏), Xi Shen(沈希), Ri-Cheng Yu(禹日成), Ting-Shan Chan(詹丁山), Lun-Xiong Li(李论雄), Guang-Hui Zhou(周光辉), Yi-feng Yang(杨义峰), Chang-Qing Jin(靳常青), You-Wen Long(龙有文)
Chin. Phys. B, 2018, 27 (3): 037503 doi: 10.1088/1674-1056/27/3/037503
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A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions. It crystallizes in a B-site disordered Pbnm perovskite structure. The charge combination is determined to be Cr5+/Fe3+ with the presence of unusual Cr5+ state in octahedral coordination, although Cr4+ and Fe4+ occur in the related perovskites CaCrO3 and CaFeO3. The randomly distributed Cr5+ and Fe3+ spins lead to short-range ferromagnetic coupling, whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe3+-O-Fe3+ interaction. In spite of the B-site Cr5+/Fe3+ disorder, the compound exhibits electrical insulating behavior. First-principles calculations further demonstrate the formation of CaCr0.55+Fe0.53+O3 charge combination, and the electron correlation effect of Fe3+ plays an important role for the insulting ground state. CaCr0.5Fe0.5O3 provides the first Cr5+ perovskite system with octahedral coordination, opening a new avenue to explore novel transition-metal oxides with exotic charge states.

NMR evidence of charge fluctuations in multiferroic CuBr2 Hot!

Rui-Qi Wang(王瑞琦), Jia-Cheng Zheng(郑家成), Tao Chen(陈涛), Peng-Shuai Wang(王朋帅), Jin-Shan Zhang(张金珊), Yi Cui(崔祎), Chao Wang(王超), Yuan Li(李源), Sheng Xu(徐胜), Feng Yuan(袁峰), Wei-Qiang Yu(于伟强)
Chin. Phys. B, 2018, 27 (3): 037502 doi: 10.1088/1674-1056/27/3/037502
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We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance (NQR), and zero-field nuclear magnetic resonance (NMR) measurements on single crystals of multiferroics CuBr2. High quality of the sample is demonstrated by the sharp magnetic and magnetic-driven ferroelectric transition at TN=TC≈ 74 K. The zero-field 79Br and 81Br NMR are resolved below TN. The spin-lattice relaxation rates reveal charge fluctuations when cooled below 60 K. Evidences of an increase of NMR linewidth, a reduction of dielectric constant, and an increase of magnetic susceptibility are also seen at low temperatures. These data suggest an emergent instability which competes with the spiral magnetic ordering and the ferroelectricity. Candidate mechanisms are discussed based on the quasi-one-dimensional nature of the magnetic system.

Phase diagram, correlations, and quantum critical point in the periodic Anderson model Hot!

Jian-Wei Yang(杨建伟), Qiao-Ni Chen(陈巧妮)
Chin. Phys. B, 2018, 27 (3): 037101 doi: 10.1088/1674-1056/27/3/037101
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Periodic Anderson model is one of the most important models in the field of strongly correlated electrons. With the recent developed numerical method density matrix embedding theory, we study the ground state properties of the periodic Anderson model on a two-dimensional square lattice. We systematically investigate the phase diagram away from half filling. We find three different phases in this region, which are distinguished by the local moment and the spin-spin correlation functions. The phase transition between the two antiferromagnetic phases is of first order. It is the so-called Lifshitz transition accompanied by a reconstruction of the Fermi surface. As the filling is close to half filling, there is no difference between the two antiferromagnetic phases. From the results of the spin-spin correlation, we find that the Kondo singlet is formed even in the antiferromagnetic phase.

4.3 THz quantum-well photodetectors with high detection sensitivity Hot!

Zhenzhen Zhang(张真真), Zhanglong Fu(符张龙), Xuguang Guo(郭旭光), Juncheng Cao(曹俊诚)
Chin. Phys. B, 2018, 27 (3): 030701 doi: 10.1088/1674-1056/27/3/030701
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We demonstrate a high performance GaAs/AlGaAs-based quantum-well photodetector (QWP) device with a peak response frequency of 4.3 THz. The negative differential resistance (NDR) phenomenon is found in the dark current-voltage (I-V) curve in the current sweeping measurement mode, from which the breakdown voltage is determined. The photocurrent spectra and blackbody current responsivities at different voltages are measured. Based on the experimental data, the peak responsivity of 0.3 A/W (at 0.15 V, 8 K) is derived, and the detection sensitivity is higher than 1011 Jones, which is in the similar level as that of the commercialized liquid-helium-cooled silicon bolometers. We attribute the high detection performance of the device to the small ohmic contact resistance of ~2Ω and the big breakdown bias.

Photonic generation of RF and microwave signal with relative frequency instability of 10-15 Hot!

Lu-Lu Yan(闫露露), Wen-Yu Zhao(赵文宇), Yan-Yan Zhang(张颜艳), Zhao-Yang Tai(邰朝阳), Pan Zhang(张攀), Bing-Jie Rao(饶冰洁), Kai Ning(宁凯), Xiao-Fei Zhang(张晓斐), Wen-Ge Guo(郭文阁), Shou-Gang Zhang(张首刚), Hai-Feng Jiang(姜海峰)
Chin. Phys. B, 2018, 27 (3): 030601 doi: 10.1088/1674-1056/27/3/030601
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We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards. These sources are realized by using photonic generation approach, and composed of ultra-stable lasers, optical-frequency-combs, optical signal detecting parts, and synthesizers. Preliminary evaluation shows that the sources produce fixed-frequency at 9.54(/9.63) GHz, 10 MHz, and tunable-frequency around 9.192 GHz with relative frequency instability of 10-15 for short terms.

Strontium optical lattice clock at the National Time Service Center Hot!

Ye-Bing Wang(王叶兵), Mo-Juan Yin(尹默娟), Jie Ren(任洁), Qin-Fang Xu(徐琴芳), Ben-Quan Lu(卢本全), Jian-Xin Han(韩建新), Yang Guo(郭阳), Hong Chang(常宏)
Chin. Phys. B, 2018, 27 (2): 023701 doi: 10.1088/1674-1056/27/2/023701
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We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock peak is 3.9 Hz with a clock laser pulse length of 300 ms, which corresponds to a Fourier-limited linewidth of 3 Hz. The fitting of the in-loop error signal data shows that the instability is approximately 5×10-15τ-1/2, affected primarily by the white noise. The fractional frequency difference averages down to 5.7×10-17 for an averaging time of 3000 s.

Magnetic field aligned orderly arrangement of Fe3O4 nanoparticles in CS/PVA/Fe3O4 membranes Hot!

Meng Du(杜萌), Xing-Zhong Cao(曹兴忠), Rui Xia(夏锐), Zhong-Po Zhou(周忠坡), Shuo-Xue Jin(靳硕学), Bao-Yi Wang(王宝义)
Chin. Phys. B, 2018, 27 (2): 027805 doi: 10.1088/1674-1056/27/2/027805
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The CS/PVA/Fe3O4 nanocomposite membranes with chainlike arrangement of Fe3O4 nanoparticles are prepared by a magnetic-field-assisted solution casting method. The aim of this work is to investigate the relationship between the microstructure of the magnetic anisotropic CS/PVA/Fe3O4 membrane and the evolved macroscopic physicochemical property. With the same doping content, the relative crystallinity of CS/PVA/Fe3O4-M is lower than that of CS/PVA/Fe3O4. The Fourier transform infrared spectroscopy (FT-TR) measurements indicate that there is no chemical bonding between polymer molecule and Fe3O4 nanoparticle. The Fe3O4 nanoparticles in CS/PVA/Fe3O4 and CS/PVA/Fe3O4-M are wrapped by the chains of CS/PVA, which is also confirmed by scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. The saturation magnetization value of CS/PVA/Fe3O4-M obviously increases compared with that of non-magnetic aligned membrane, meanwhile the transmittance decreases in the UV-visible region. The o-Ps lifetime distribution provides information about the free-volume nanoholes present in the amorphous region. It is suggested that the microstructure of CS/PVA/Fe3O4 membrane can be modified in its curing process under a magnetic field, which could affect the magnetic properties and the transmittance of nanocomposite membrane. In brief, a full understanding of the relationship between the microstructure and the macroscopic property of CS/PVA/Fe3O4 nanocomposite plays a vital role in exploring and designing the novel multifunctional materials.

Magnetocaloric effect in the layered organic-inorganic hybrid (CH3NH3)2CuCl4 Hot!

Yinina Ma(马怡妮娜), Kun Zhai(翟昆), Liqin Yan(闫丽琴), Yisheng Chai(柴一晟), Dashan Shang(尚大山), Young Sun(孙阳)
Chin. Phys. B, 2018, 27 (2): 027501 doi: 10.1088/1674-1056/27/2/027501
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We present a study of magnetocaloric effect of the quasi-two-dimensional (2D) ferromagnet (CH3NH3)2CuCl4 in ab plane (easy-plane). From the measurements of magnetic field dependence of magnetization at various temperatures, we have discovered a large magnetic entropy change associated with the ferromagnetic-paramagnetic transition. The heat capacity measurements reveal an abnormal adiabatic change below the Curie temperature Tc~8.9 K, which is caused by the nature of quasi-2D layered crystal structure. These results suggest that perovskite organic-inorganic hybrids with a layered structure are suitable candidates as working substances in magnetic refrigeration technology.

Arbitrated quantum signature scheme with continuous-variable squeezed vacuum states Hot!

Yan-Yan Feng(冯艳艳), Rong-Hua Shi(施荣华), Ying Guo(郭迎)
Chin. Phys. B, 2018, 27 (2): 020302 doi: 10.1088/1674-1056/27/2/020302
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We propose an arbitrated quantum signature (AQS) scheme with continuous variable (CV) squeezed vacuum states, which requires three parties, i.e., the signer Alice, the verifier Bob and the arbitrator Charlie trusted by Alice and Bob, and three phases consisting of the initial phase, the signature phase and the verification phase. We evaluate and compare the original state and the teleported state by using the fidelity and the beam splitter (BS) strategy. The security is ensured by the CV-based quantum key distribution (CV-QKD) and quantum teleportation of squeezed states. Security analyses show that the generated signature can be neither disavowed by the signer and the receiver nor counterfeited by anyone with the shared keys. Furthermore, the scheme can also detect other manners of potential attack although they may be successful. Also, the integrality and authenticity of the transmitted messages can be guaranteed. Compared to the signature scheme of CV-based coherent states, our scheme has better encoding efficiency and performance. It is a potential high-speed quantum signature scheme with high repetition rate and detection efficiency which can be achieved by using the standard off-the-shelf components when compared to the discrete-variable (DV) quantum signature scheme.

Optical study on intermediate-valence compounds Yb1-xLuxAl3 Hot!

J L Lv(吕佳林), J L Luo(雒建林), N L Wang(王楠林)
Chin. Phys. B, 2018, 27 (1): 017803 doi: 10.1088/1674-1056/27/1/017803
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We report an optical spectroscopy study on intermediate valence system Yb1-xLuxAl3 with x=0, 0.25, 0.5, 0.75, and 1. The Kondo temperature in the system is known to increase with increasing Lu concentration. Therefore, it is expected that the energy scale of the hybridization gap should increase with increasing Lu concentration based on the periodic Anderson model. On the contrary, we find that the spectral structure associated with the hybridization effect shifts monotonically to lower energy. Furthermore, the Lu substitution results in a substantial increase of the free carrier spectral weight and less pronounced plasma frequency reduction upon lowering temperature. We attribute the effect to the disruption of the Kondo lattice periodicity by the random substitution of Yb by Lu. The work highlights the importance of the lattice periodicity of the rare earth element for understanding the Kondo lattice phenomena.

Measurement of the bulk and surface bands in Dirac line-node semimetal ZrSiS Hot!

Guang-Hao Hong(洪光昊), Cheng-Wei Wang(王成玮), Juan Jiang(姜娟), Cheng Chen(陈成), Sheng-Tao Cui(崔胜涛), Hai-Feng Yang(杨海峰), Ai-Ji Liang(梁爱基), Shuai Liu(刘帅), Yang-Yang Lv(吕洋洋), Jian Zhou(周健), Yan-Bin Chen(陈延彬), Shu-Hua Yao(姚淑华), Ming-Hui Lu(卢明辉), Yan-Feng Chen(陈延峰), Mei-Xiao Wang(王美晓), Le-Xian Yang(杨乐仙), Zhong-Kai Liu(柳仲楷), Yu-Lin Chen(陈宇林)
Chin. Phys. B, 2018, 27 (1): 017105 doi: 10.1088/1674-1056/27/1/017105
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Dirac semimetals are materials in which the conduction and the valence bands have robust crossing points protected by topology or symmetry. Recently, a new type of Dirac semimetals, so called the Dirac line-node semimetals (DLNSs), have attracted a lot of attention, as they host robust Dirac points along the one-dimensional (1D) lines in the Brillouin zone (BZ). In this work, using angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations, we systematically investigated the electronic structures of non-symmorphic ZrSiS crystal where we clearly distinguished the surface states from the bulk states. The photon-energy-dependent measurements further prove the existence of Dirac line node along the X-R direction. Remarkably, by in situ surface potassium doping, we clearly observed the different evolutions of the bulk and surface electronic states while proving the robustness of the Dirac line node. Our studies not only reveal the complete electronic structures of ZrSiS, but also demonstrate the method manipulating the electronic structure of the compound.

Direct observation of melted Mott state evidenced from Raman scattering in 1T-TaS2 single crystal Hot!

Qing Hu(胡庆), Cong Yin(尹聪), Leilei Zhang(张雷雷), Li Lei(雷力), Zhengshang Wang(王正上), Zhiyu Chen(陈志禹), Jun Tang(唐军), Ran Ang(昂然)
Chin. Phys. B, 2018, 27 (1): 017104 doi: 10.1088/1674-1056/27/1/017104
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The evolution of electron correlation and charge density wave (CDW) in 1T-TaS2 single crystal has been investigated by temperature-dependent Raman scattering, which undergoes two obvious peaks of A1g modes about 70.8 cm-1 and 78.7 cm-1 at 80 K, respectively. The former peak at 70.8 cm-1 is accordant with the lower Hubbard band, resulting in the electron-correlation-driven Mott transition. Strikingly, the latter peak at 78.7 cm-1 shifts toward low energy with increasing the temperature, demonstrating the occurrence of nearly commensurate CDW phase (melted Mott phase). In this case, phonon transmission could be strongly coupled to commensurate CDW lattice via Coulomb interaction, which likely induces appearance of hexagonal domains suspended in an interdomain phase, composing the melted Mott phase characterized by a shallow electron pocket. Combining electronic structure, atomic structure, transport properties with Raman scattering, these findings provide a novel dimension in understanding the relationship between electronic correlation, charge order, and phonon dynamics.

Two-dimensional transport and strong spin-orbit interaction in SrMnSb2 Hot!

Jiwei Ling(凌霁玮), Yanwen Liu(刘彦闻), Zhao Jin(金昭), Sha Huang(黄沙), Weiyi Wang(王伟懿), Cheng Zhang(张成), Xiang Yuan(袁翔), Shanshan Liu(刘姗姗), Enze Zhang(张恩泽), Ce Huang(黄策), Raman Sankar, Fang-Cheng Chou, Zhengcai Xia(夏正才), Faxian Xiu(修发贤)
Chin. Phys. B, 2018, 27 (1): 017504 doi: 10.1088/1674-1056/27/1/017504
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We have carried out magneto-transport measurements for single crystal SrMnSb2. Clear Shubnikov-de Haas oscillations were resolved at relatively low magnetic field around 4 T, revealing a quasi-2D Fermi surface. We observed a development of quantized plateaus in Hall resistance (Rxy) at high pulsed fields up to 60 T. Due to the strong 2D confinement and layered properties of the samples, we interpreted the observation as bulk quantum Hall effect that is contributed by the parallel 2D conduction channels. Moreover, the spin degeneracy was lifted leading to Landau level splitting. The presence of anisotropic g factor and the formation of the oscillation beating pattern reveal a strong spin-orbit interaction in the SrMnSb2 system.

Quantum oscillations and nontrivial transport in (Bi0.92In0.08)2Se3 Hot!

Minhao Zhang(张敏昊), Yan Li(李焱), Fengqi Song(宋凤麒), Xuefeng Wang(王学锋), Rong Zhang(张荣)
Chin. Phys. B, 2017, 26 (12): 127305 doi: 10.1088/1674-1056/26/12/127305
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Quantum phase transition in topological insulators has drawn heightened attention in condensed matter physics and future device applications. Here we report the magnetotransport properties of single crystalline (Bi0.92In0.08)2Se3. The average mobility of~1000 cm2·V-1·s-1 is obtained from the Lorentz law at the low field (< 3 T) up to 50 K. The quantum oscillations rise at a field of~5 T, revealing a high mobility of~1.4×104 cm2·V-1·s-1 at 2 K. The Dirac surface state is evident by the nontrivial Berry phase in the Landau-Fan diagram. The properties make the (Bi0.92In0.08)2Se3 a promising platform for the investigation of quantum phase transition in topological insulators.

Finite element analysis of ionic liquid gel soft actuator Hot!

Bin He(何斌), Cheng-Hong Zhang(张成红), An Ding(丁安)
Chin. Phys. B, 2017, 26 (12): 126102 doi: 10.1088/1674-1056/26/12/126102
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A new type of soft actuator material-ionic liquid gel (ILG), which consists of HEMA, BMIMBF4, and TiO2, can be transformed into gel state under the irradiation of ultraviolet (UV) light. In this paper, Mooney-Rivlin hyperelastic model of finite element method is proposed for the first time to study the properties of the ILG. It has been proved that the content of TiO2 has a great influence on the properties of the gel, and Young's modulus of the gel increases with the increase of its content, despite of reduced tensile deformation. The results in this work show that when the TiO2 content is 1.0 wt%, a large tensile deformation and a strong Young's modulus can be obtained to be 325% and 7.8 kPa, respectively. The material parameters of ILG with TiO2 content values of 0.2 wt%, 0.5 wt%, 1.0 wt%, and 1.5 wt% are obtained, respectively, through uniaxial tensile tests, including C10, C01, C20, C11, C02, C30, C21, C12, and C03 elements. In this paper, the large-scaled general finite element software ANSYS is used to simulate and analyze the ILG, which is based on SOLID186 element and nonlinear hyperelastic Mooney-Rivlin model. The finite element simulation analysis based stress-strain curves are almost consistent with the experimental stress-strain curves, and hence the finite element analysis of ILG is feasible and credible. This work presents a new direction for studying the performance of soft actuator for the ILG, and also contributes to the design of soft robot actuator.

Output light power of InGaN-based violet laser diodes improved by using a u-InGaN/GaN/AlGaN multiple upper waveguide Hot!

Feng Liang(梁锋), De-Gang Zhao(赵德刚), De-Sheng Jiang(江德生), Zong-Shun Liu(刘宗顺), Jian-Jun Zhu(朱建军), Ping Chen(陈平), Jing Yang(杨静), Wei Liu(刘炜), Shuang-Tao Liu(刘双韬), Yao Xing(邢瑶), Li-Qun Zhang(张立群), Wen-Jie Wang(王文杰), Mo Li(李沫), Yuan-Tao Zhang(张源涛), Guo-Tong Du(杜国同)
Chin. Phys. B, 2017, 26 (12): 124210 doi: 10.1088/1674-1056/26/12/124210
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The upper waveguide (UWG) has direct influences on the optical and electrical characteristics of the violet laser diode (LD) by changing the optical field distribution or barrier of the electron blocking layer (EBL). In this study, a series of InGaN-based violet LDs with different UWGs are investigated systematically with LASTIP software. It is found that the output light power (OLP) under an injecting current of 120 mA or the threshold current (Ith) is deteriorated when the UWG is u-In0.02Ga0.98N/GaN or u-In0.02Ga0.98N/AlxGa1-xN (0 ≤ x ≤ 0.1), which should be attributed to small optical confinement factor (OCF) or severe electron leakage. Therefore, a new violet LD structure with u-In0.02Ga0.98N/GaN/Al0.05Ga0.95N multiple layer UWG is proposed to reduce the optical loss and increase the barrier of EBL. Finally, the output light power under an injecting current of 120 mA is improved to 176.4 mW.

Improvement of laser damage thresholds of fused silica by ultrasonic-assisted hydrofluoric acid etching Hot!

Yuan Li(李源), Hongwei Yan(严鸿维), Ke Yang(杨科), Caizhen Yao(姚彩珍), Zhiqiang Wang(王志强), Chunyan Yan(闫春燕), Xinshu Zou(邹鑫书), Xiaodong Yuan(袁晓东), Liming Yang(杨李茗), Xin Ju(巨新)
Chin. Phys. B, 2017, 26 (11): 118104 doi: 10.1088/1674-1056/26/11/118104
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Polished fused silica samples were etched for different durations by using hydrofluoric (HF) acid solution with HF concentrations in an ultrasonic field. Surface and subsurface polishing residues and molecular structure parameters before and after the etching process were characterized by using a fluorescence microscope and infrared (IR) spectrometer, respectively. The laser induced damage thresholds (LIDTs) of the samples were measured by using pulsed nanosecond laser with wavelength of 355 nm. The results showed that surface and subsurface polishing residues can be effectively reduced by the acid etching process, and the LIDTs of fused silica are significantly improved. The etching effects increased with the increase of the HF concentration from 5 wt.% to 40 wt.%. The amount of polishing residues decreased with the increase of the etching duration and then kept stable. Simultaneously, with the increase of the etching time, the mechanical strength and molecular structure were improved.

An easy way to controllably synthesize one-dimensional SmB6 topological insulator nanostructures and exploration of their field emission applications Hot!

Xun Yang(杨汛), Hai-Bo Gan(甘海波), Yan Tian(田颜), Ning-Sheng Xu(许宁生), Shao-Zhi Deng(邓少芝), Jun Chen(陈军), Huanjun Chen(陈焕君), Shi-Dong Liang(梁世东), Fei Liu(刘飞)
Chin. Phys. B, 2017, 26 (11): 118103 doi: 10.1088/1674-1056/26/11/118103
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A convenient fabrication technique for samarium hexaboride (SmB6) nanostructures (nanowires and nanopencils) is developed, combining magnetron-sputtering and chemical vapor deposition. Both nanostructures are proven to be single crystals with cubic structure, and they both grow along the[001] direction. Formation of both nanostructures is attributed to the vapor-liquid-solid (VLS) mechanism, and the content of boron vapor is proposed to be the reason for their different morphologies at various evaporation distances. Field emission (FE) measurements show that the maximum current density of both the as-grown nanowires and nanopencils can be several hundred μA/cm2, and their FN plots deviate only slightly from a straight line. Moreover, we prefer the generalized Schottky-Nordheim (SN) model to comprehend the difference in FE properties between the nanowires and nanopencils. The results reveal that the nonlinearity of FN plots is attributable to the effect of image potential on the FE process, which is almost independent of the morphology of the nanostructures. All the research results suggest that the SmB6 nanostructures would have a more promising future in the FE area if their surface oxide layer was eliminated in advance.

Fluctuating specific heat in two-band superconductors Hot!

Lei Qiao(乔雷), Cheng Chi(迟诚), Jiangfan Wang(王江帆)
Chin. Phys. B, 2017, 26 (11): 117401 doi: 10.1088/1674-1056/26/11/117401
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Theory of thermal fluctuations in two-band superconductors under an essentially homogeneous magnetic field is developed within the framework of the two-band Ginzburg-Landau theory. The fluctuating specific heat is calculated by using the optimized self-consistent perturbation approach and the results are applied to analyze the thermodynamic data of the iron-based superconductors Ba1-xKxFe2As2 with x~0.4, which have been suggested to have a two-band structure by recent experiments. We estimate the fluctuation strength in this material and find that the specific heat is described well with the Ginzburg number Gi=4·10-4. The influence of interband coupling strength is investigated and the result of the two-band Gaussian approximation approach is compared.

Interfacial nanobubbles produced by long-time preserved cold water Hot!

Li-Min Zhou(周利民), Shuo Wang(王硕), Jie Qiu(邱杰), Lei Wang(王磊), Xing-Ya Wang(王兴亚), Bin Li(李宾), Li-Juan Zhang(张立娟), Jun Hu(胡钧)
Chin. Phys. B, 2017, 26 (10): 106803 doi: 10.1088/1674-1056/26/10/106803
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Interfacial gaseous nanobubbles which have remarkable properties such as unexpectedly long lifetime and significant potential applications, are drawing more and more attention. However, the recent dispute about the contamination or gas inside the nanobubbles causes a large confusion due to the lack of simple and clean method to produce gas nanobubbles. Here we report a convenient and clean method to effectively produce interfacial nanobubbles based on a pure water system. By adding the cold water cooled at 4 ℃ for more than 48 h onto highly oriented pyrolytic graphite (HOPG) surface, we find that the average density and total volume of nanobubbles are increased to a high level and mainly dominated by the concentrations of the dissolved gases in cold water. Our findings and methods are crucial and helpful for settling the newly arisen debates on gas nanobubbles.

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