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Coulomb-assisted nonlocal electron transport between two pairs of Majorana bound states in a superconducting island

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Chinese physics B 2024年第5期33卷 275-279页

作者：王浩迪任俊潼吕海峰柯莎莎 School of physics University of Electronic Science and Technology of ChinaChengdu 610054China

We investigate the nonlocal transport modulated by Coulomb interactions in devices comprising two interacting Majorana wires,where both nanowires are in proximity to a mesoscopic superconducting(SC)island.Each Majorana bound state(MBS)is coupled to one lead via a quantum dot with resonant levels.In this device,the nonlocal correlations can be induced in the absence of Majorana energy splitting.We find that the negative differential conductance and giant current noise cross correlation could be induced,due to the interplay between nonlocality of MBSs and dynamical Coulomb blockade effect.This feature may provide a signature for the existence of the MBSs.

关键词： Majorana bound states superconducting island current cross correlation

Highly efficient conversion from classical guided waves to topological chiral edge states

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Chinese Optics Letters 2024年第2期22卷 221-226页

作者：韩建飞梁锋赵玉林丁霄汪相如赵德双王秉中 School of physics University of Electronic Science and Technology of ChinaChengdu 611731China School of Optoelectronic science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

Electromagnetic topological chiral edge states mimicking the quantum Hall effect have attracted a great deal of attention due to their unique features of free backscattering and immunity against sharp bends and defects.However,the matching techniques between classical waveguides and the topological one-way waveguide deserve more attention for real-world applications.In this paper,a highly efficient conversion structure between a classical rectangular waveguide and a topological one-way waveguide is proposed and demonstrated at the microwave frequency,which efficiently converts classical guided waves to topological one-way edge states.A tapered transition is designed to match both the momentum and impedance of the classical guided waves and the topological one-way edge states.With the conversion structure,the waves generated by a point excitation source can be coupled to the topological one-way waveguide with very high coupling efficiency,which can ensure high transmission of the whole system(i.e.,from the source and the receiver).Simulation and measurement results demonstrate the proposed method.This investigation is beneficial to the applications of topological one-way waveguides and opens up a new avenue for advanced topological and classical integrated functional devices and systems.

关键词： guided waves highly efficient conversion photonic crystals topological chiral edge states

Quantum Anomalous Hall Effect with Tunable Chern Numbers in High-Temperature 1T-PrN_(2) Monolayer

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Chinese physics Letters 2024年第5期41卷 77-84页

作者：吴绪才李树宗司君山黄博张卫兵 Hunan Provincial Key Laboratory of Flexible electronic Materials Genome Engineering School of Physics and Electronic SciencesChangsha University of Science and TechnologyChangsha 410114China

Quantum anomalous Hall(QAH) insulators have highly potential applications in spintronic device. However,available candidates with tunable Chern numbers and high working temperature are quite rare. Here, we predict a 1T-PrN_(2) monolayer as a stable QAH insulator with high magnetic transition temperature of above 600 K and tunable high Chern numbers of C = ±3 from first-principles calculations. Without spin-orbit coupling(SOC),the 1T-PrN_(2) monolayer is predicted to be a p-state Dirac half metal with high Fermi velocity. Rich topological phases depending on magnetization directions can be found when the SOC is considered. The QAH effect with periodical changes of Chern number(±1) can be produced when the magnetic moment breaks all twofold rotational symmetries in the xy plane. The critical state can be identified as Weyl half semimetals. When the magnetization direction is parallel to the z-axis, the system exhibits high Chern number QAH effect with C = ±3.Our work provides a new material for exploring novel QAH effect and developing high-performance topological devices.

关键词： magnetization topological monolayer

Optimal and robust control of population transfer in asymmetric quantum-dot molecules

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Chinese physics B 2024年第2期33卷 353-359页

作者：郭裕马松山束传存 Hunan Provincial Key Laboratory of Flexible electronic Materials Genome Engineering School of Physics and Electronic ScienceChangsha University of Science and TechnologyChangsha 410114China Hunan Key Laboratory of Nanophotonics and Devices School of PhysicsCentral South UniversityChangsha 410083China

We present an optimal and robust quantum control method for efficient population transfer in asymmetric double quantum-dot molecules.We derive a long-duration control scheme that allows for highly efficient population transfer by accurately controlling the amplitude of a narrow-bandwidth pulse.To overcome fluctuations in control field parameters,we employ a frequency-domain quantum optimal control theory method to optimize the spectral phase of a single pulse with broad bandwidth while preserving the spectral amplitude.It is shown that this spectral-phase-only optimization approach can successfully identify robust and optimal control fields,leading to efficient population transfer to the target state while concurrently suppressing population transfer to undesired states.The method demonstrates resilience to fluctuations in control field parameters,making it a promising approach for reliable and efficient population transfer in practical applications.

关键词： population transfer quantum optimal control theory quantum-dot molecules

Pressure-triggered stacking dependence of interlayer coupling in bilayer WS2

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science China(physics,Mechanics & Astronomy) 2024年第8期Mechanics & Astronomy) .卷 181-190页

作者： Zejuan Zhang Chenyin Jiao Shenghai Pei Xilong Zhou Jiaze Qin Wanli Zhang Yu Zhou Zenghui Wang Juan Xia School of Integrated sciences and Engineering(Exemplary School of Microelectronics) University of Electronic Science and Technology of China Institute of Fundamental and Frontier sciences University of Electronic Science and Technology of China School of physics and electronics Hunan Key Laboratory of Nanophotonics and DevicesCentral South University State Key Laboratory of electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China

Tungsten disulfide（WS2） has been reported to show negligible stacking dependence under ambient conditions, impeding its further explorations on physical properties and potential applications. Here, we realize efficient modulation of interlayer coupling in bilayer WS2with 3R and 2H stackings by high pressure, and find that the pressure-triggered interlayer coupling and pressure-induced resonant-to-nonresonant transition exhibit prominent stacking dependence, which are experimentally observed for the first time in WS2. Our work may unleash the stacking degree of freedom in designing WS2devices with tailored properties correlated to interlayer coupling.

关键词： tungsten disulfide pressure engineering stacking order interlayer coupling

Recent progress of in-situ characterization of LiNi_(1−x−y)Co_(x)Mn_(y)O_(2) cathodes for lithium metal batteries: A mini review

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Nano Research 2024年第3期17卷 1384-1401页

作者： Huanzhu Lv Xiaoqi Zhu Jun Mei Yuanhua Xia Bin Wang Institute of Fundamental and Frontier science University of Electronic Science and Technology of ChinaChengdu 611731China Chengdu Development Center of science and Technology China Academy of Engineering PhysicsChengdu 610200China Key Laboratory of Neutron physics and Institute of Nuclear physics and Chemistry China Academy of Engineering Physics(CAEP)Mianyang 621999China

In the context of the gradual popularity of electric vehicles(EVs),the development of lithium battery systems with high energy density and power density is regarded as the foremost way to improve the range of EVs.LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)cathodes have been the focus of researchers due to their high energy density,excellent power performance,and low-temperature resistance.However,the elaboration of the decay mechanism of NCM cathode based on lithium metal batteries(LMBs)is still being restricted to the primary level.In the past decades,the development and application of advanced in-situ characterization tools have facilitated researchers'understanding of the internal operation mechanism of batteries during charging and discharging.In this minireview,the latest progress of in-situ observation of the NCM cathode by X-ray diffraction(XRD),fourier transform infrared(FT-IR)spectroscopy,Raman spectroscopy,atomic force microscopy(AFM),transmission electron microscope(TEM),optical microscope,and other characterization tools is summarized.The mechanisms of structural degradation,cathode-electrolyte interfaces(CEIs)composition,and dynamic changes of NCM,electrolyte breakdown,and gas production are elaborated.Finally,based on the existing research progress,the opportunities and challenges for future in-situ characterization technology in the study of the mechanism of LMBs are discussed in depth.Therefore,the purpose of this minireview is to summarize recent work that focuses on the outstanding application of in-situ characterization techniques in the mechanistic study of LMBs,and pointing the way to the future development of high energy density and power density LMBs systems.

关键词： lithium metal batteries(LMBs) In-situ characterization LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)

Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators

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National science Review 2024年第2期11卷 15-23页

作者： Rui Chen Hai-Peng Sun Mingqiang Gu Chun-Bo Hua Qihang Liu Hai-Zhou Lu X.C.Xie Shenzhen Institute for Quantum science and Engineering and Department of physics Southern University of Science and Technology(SUSTech) International Quantum Academy Institute for Theoretical physics and Astrophysics University of Würzburg School of electronic and Information Engineering Hubei University of Science and Technology Guangdong Provincial Key Laboratory of Computational science and Material Design Southern University of Science and Technology Shenzhen Key Laboratory of Quantum science and Engineering International Center for Quantum Materials School of PhysicsPeking University Collaborative Innovation Center of Quantum Matter CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences

The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.

关键词： layerHall effect hidden Berry curvature antiferromagnetic insulator axion insulator, quantum transport

Spin transport characteristics modulated by the GeBi interlayer in Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures

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Chinese physics B 2024年第2期33卷 471-475页

作者：李明明张磊金立川郭海中 Key Laboratory of Materials physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China State Key Laboratory of electronic Thin Films&Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China Institute of Quantum Materials and physics Henan Academy of SciencesZhengzhou 450046China

For the past few years,germanium-based semiconductor spintronics has attracted considerable interest due to its potential for integration into mainstream semiconductor technology.The main challenges in the development of modern semiconductor spintronics are the generation,detection,and manipulation of spin currents.Here,the transport characteristics of a spin current generated by spin pumping through a GeBi semiconductor barrier in Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures were investigated systematically.The effective spin-mixing conductance and inverse spin Hall voltage to quantitatively describe the spin transport characteristics were extracted.The spin-injection efficiency in the Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures is comparable to that of the Y_(3)Fe_(5)O_(12)/Pt bilayer,and the inverse spin Hall voltage exponential decays with the increase in the barrier thickness.Furthermore,the band gap of the GeBi layer was tuned by changing the Bi content.The spin-injection efficiency at the YIG/semiconductor interface and the spin transportation within the semiconductor barrier are related to the band gap of the GeBi layer.Our results may be used as guidelines for the fabrication of efficient spin transmission structures and may lead to further studies on the impacts of different kinds of barrier materials.

关键词： spin current Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures spin pumping inverse spin Hall effect

Enhancing thermoelectric performance of p-type SnTe through manipulating energy band structures and decreasing electronic thermal conductivity

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Rare Metals 2024年第7期43卷 3232-3241页

作者： Xin Qian Hao-Ran Guo Jia-Xin Lyu Bang-Fu Ding Xing-Yuan San Xiao Zhang Jiang-Long Wang Shu-Fang Wang Hebei Key Lab of Optic-electronic Information and Materials College of Physics Science and TechnologyHebei University College of Electron and Information Engineering Hebei University Research Institute for Frontier science Beihang University

SnTe has received considerable attention as an environmentally friendly alternative to the representative thermoelectric material of PbTe.However,excessive hole carrier concentration in SnTe results in an extremely low Seebeck coefficient and high thermal conductivity,which makes it exhibit relatively inferior thermoelectric properties.In this work,the thermoelectric performance of p-type SnTe is enhanced through regulating its energy band structures and reducing its electronic thermal conductivity by combining Bi doping with CdSe alloying.First,the carrier concentration of SnTe is successfully suppressed via Bi doping,which significantly decreases the electronic thermal conductivity.Then,the convergence and flattening of the valence bands by alloying CdSe effectively improves the effective mass of SnTe while restraining its carrier mobility.Finally,a maximum figure of merit（ZT） of～ 0.87 at 823 K and an average ZT of～ 0.51 at 300-823 K have been achieved in Sn0.96Bi0.04Te-5%CdSe.Our results indicate that decreasing the electronic thermal conductivity is an effective means of improving the performance of thermoelectric materials with a high carrier concentration.

关键词： Thermoelectric materials SnTe Energy band structure electronic thermal conductivity ZT value