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Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

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Chinese physics B 2024年第6期33卷 596-603页

作者：吕小龙杨加恩谢航 College of Science Guangxi University of Science and TechnologyLiuzhou 545006China College of physics Chongqing UniversityChongqing 401331China chongqing key laboratory for strongly-coupled physics Chongqing UniversityChongqing 401331China

Topological zero-line modes(ZLMs) with spin and valley degrees of freedom give rise to spin, valley and spinvalley transport, which support a platform for exploring quantum transport physics and potential applications in spintronic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current due to the ZLMs in a three-terminal system. We show that with certain combinations of ZLMs, the incident charge current along the interface between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals. As a result, fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. The mechanism of these splitters is attributed to the cooperative effects of the distribution of the ZLMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch. Interestingly, half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam splitter.Furthermore, the results indicate that these splitters can be applicable to graphene, silicene, germanene and stanene due to their robustness against the spin–orbit coupling. Our findings offer a new way to understand the transport mechanism and investigate the promising applications of ZLMs.

关键词： topological zero-line modes spin polarization valley polarization quantum transport

A proposal for detecting weak electromagnetic waves around 2.6μm wavelength with Sr optical clock

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Chinese physics B 2024年第4期33卷 452-457页

作者：韩弱水王伟汪涛 Department of physics and Chongqing Key Laboratory for Strongly Coupled PhysicsChongqing UniversityChongqing 401331China Center of Modern physics Institute for Smart City of Chongqing University in LiyangLiyang 213300China State key laboratory of Quantum Optics and Quantum Optics Devices Shanxi UniversityTaiyuan 030006China

Infrared signal detection is widely used in many fields.Due to the detection principle,however,the accuracy and range of detection are limited.Thanks to the ultra stability of the^(87)Sr optical lattice clock,external infrared electromagnetic wave disturbances can be responded to.Utilizing the ac Stark shift of the clock transition,we propose a new method to detect infrared signals.According to our calculations,the theoretical detection accuracy in the vicinity of its resonance band of 2.6μm can reach the order of 10-14W,while the minimum detectable signal of common detectors is on the order of 10^(-10)W.

关键词： infrared signal detection ^(87)Sr optical lattice clock ac Stark shift ultra stability

Photoinduced Floquet higher-order Weyl semimetal in C_(6) symmetric Dirac semimetals

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Chinese physics B 2024年第6期33卷 109-117页

作者：许欣欣王梓名许东辉陈垂针 Institute for Advanced Study and School of Physical Science and Technology Soochow UniversitySuzhou 215006China Department of physics and chongqing key laboratory for strongly coupled physics Chongqing UniversityChongqing 400044China Center of Quantum Materials and Devices Chongqing UniversityChongqing 400044China

Topological Dirac semimetals are a parent state from which other exotic topological phases of matter, such as Weyl semimetals and topological insulators, can emerge. In this study, we investigate a Dirac semimetal possessing sixfold rotational symmetry and hosting higher-order topological hinge Fermi arc states, which is irradiated by circularly polarized light. Our findings reveal that circularly polarized light splits each Dirac node into a pair of Weyl nodes due to the breaking of time-reversal symmetry, resulting in the realization of the Weyl semimetal phase. This Weyl semimetal phase exhibits rich boundary states, including two-dimensional surface Fermi arc states and hinge Fermi arc states confined to six hinges.Furthermore, by adjusting the incident direction of the circularly polarized light, we can control the degree of tilt of the resulting Weyl cones, enabling the realization of different types of Weyl semimetals.

关键词： Dirac semimetals Weyl semimetals periodic driving higher-order topology

Revisiting the top-quark pair production at future e^(+)e^(−)colliders

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Chinese physics C 2024年第4期48卷 82-88页

作者：马进王声权孙婷申建明吴兴刚 Department of physics Guizhou Minzu UniversityGuiyang 550025China School of physics and Electronics Hunan Provincial Key Laboratory of High-Energy Scale Physics and ApplicationsHunan UniversityChangsha 410082China Department of physics Chongqing Key Laboratory for Strongly Coupled PhysicsChongqing UniversityChongqing 401331China

In this study,we reanalyze the top-quark pair production at next-to-next-to-leading order(NNLO)in quantum chromodynamics(QCD)at future e^(+)e^(−)colliders using the Principle of Maximum Conformality(PMC)method.The PMC renormalization scales inαs are determined by absorbing the non-conformalβterms by recursively using the Renormalization Group Equation(RGE).Unlike the conventional scale-setting method of fixing the scale at the center-of-mass energyμ_(r)=√s,the determined PMC scale Q_(⋆)is far smaller than the √sand increases with the √s,yielding the correct physical behavior for the top-quark pair production process.Moreover,the convergence of the pQCD series for the top-quark pair production is greatly improved owing to the elimination of the renormalon divergence.For a typical collision energy of √s=500 GeV,the PMC scale is Q_(⋆)=107 GeV;the QCD correction factor K for conventional results is K∼1+0.1244+0.0102+0.0012−0.0087−0.0011+0.0184−0.0086+0.0002+0.0061−0.0003,where the first error is caused by varying the scaleμr∈[√s/2,2√s]and the second error is from the top-quark massΔm_(t)=±0.7 GeV.After applying the PMC,the renormalization scale uncertainty is eliminated,and the QCD correction factor K is improved to K∼1+0.1507_(−0.0015)^(+0.0015)−0.0057_(−0.0000)^(+0.0001),where the error is from the top-quark massΔm_(t)=±0.7 GeV.The PMC improved predictions for the top-quark pair production are helpful for detailed studies of the properties of the top-quark at future e^(+)e^(−)colliders.

关键词： top-quark lepton colliders Renormalization Group Equation QCD correction

Precise determination of the top-quark on-shell mass Mt via its scale-invariant perturbative relation to the top-quark MS mass m_(t)(m_(t))

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Chinese physics C 2024年第5期48卷 180-193页

作者：黄旭东吴兴刚郑绪昌闫江吴知非马鸿浩 Institute of High Energy physics Chinese Academy of SciencesBeijing 100049China Department of physics Chongqing Key Laboratory for Strongly Coupled PhysicsChongqing UniversityChongqing 401331China Department of physics Guangxi Normal UniversityGuilin 541004China

The principle of maximum conformality(PMC)provides a systematic approach to solve the conventional renormalization scheme and scale ambiguities.Scale-fixed predictions of physical observables using the PMC are independent of the choice of renormalization scheme–a key requirement for renormalization group invariance.In this paper,we derive new degeneracy relations based on the renormalization group equations that involve both the usualβ-function and the quark mass anomalous dimensionγm-function.These new degeneracy relations enable improved PMC scale-setting procedures for correct magnitudes of the strong coupling constant and MS¯-running quark mass to be determined simultaneously.By using these improved PMC scale-setting procedures,the renormalization scale dependence of the MS¯-on-shell quark mass relation can be eliminated systematically.Consequently,the top-quark on-shell(or MS¯)mass can be determined without conventional renormalization scale ambiguity.Taking the top-quark MS¯mass m¯t(m¯t)=162.5+2.1−1.5 GeV as the input,we obtain Mt≃172.41+2.21−1.57 GeV.Here,the uncertainties arise from errors combined with those fromΔαs(MZ)and the approximate uncertainty resulting from the uncalculated five-loop terms predicted through the Padéapproximation approach.

关键词： perturbative QCD top quark mass renormalization

Electronic structure and effective mass of pristine and Cl-doped CsPbBr_(3)

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Chinese physics B 2024年第5期33卷 167-171页

作者：魏志远魏愉昊徐申东彭舒婷 Makoto Hashimoto 路东辉潘旭匡泯泉肖正国何俊峰 Department of physics and CAS key laboratory of strongly-coupled Quantum Matter physics University of Science and Technology of ChinaHefei 230026China chongqing key laboratory of Micro & Nano Structure Optoelectronics and School of Physical Science and TechnologySouthwest UniversityChongqing 400715China key laboratory of Photovoltaic and Energy Conservation Materials Institute of Applied TechnologyHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Stanford Synchrotron Radiation Lightsource and Stanford Institute for Materials and Energy Sciences SLAC National Accelerator LaboratoryMenlo ParkCalifornia 94025USA

Organic–inorganic lead halide perovskites(LHPs) have attracted great interest owing to their outstanding optoelectronic properties.Typically,the underlying electronic structure would determinate the physical properties of materials.But as for now,limited studies have been done to reveal the underlying electronic structure of this material system,comparing to the huge amount of investigations on the material synthesis.The effective mass of the valance band is one of the most important physical parameters which plays a dominant role in charge transport and photovoltaic phenomena.In pristine CsPbBr_(3),the Fr?hlich polarons associated with the Pb–Br stretching modes are proposed to be responsible for the effective mass renormalization.In this regard,it would be very interesting to explore the electronic structure in doped LHPs.Here,we report high-resolution angle-resolved photoemission spectroscopy(ARPES) studies on both pristine and Cl-doped CsPbBr_(3).The experimental band dispersions are extracted from ARPES spectra along both ■ and ■ high symmetry directions.DFT calculations are performed and directly compared with the ARPES data.Our results have revealed the band structure of Cl-doped CsPbBr_(3) for the first time,which have also unveiled the effective mass renormalization in the Cl-doped CsPbBr_(3) compound.Doping dependent measurements indicate that the chlorine doping could moderately tune the renormalization strength.These results will help understand the physical properties of LHPs as a function of doping.

关键词： lead halide perovskites electronic structure effective mass

Interplay between the atomic structures and superconductivity of two-monolayer Pb films

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Science China(physics,Mechanics & Astronomy) 2024年第1期67卷 90-98页

作者： Kun Xie Ze Huang Pengju Li Yumin Xia Desheng Cai Yitong Gu Yuzhou Liu Fangliang Cai Runxiao Zhang Haohao Shi Ping Cui Shengyong Qin International Center for Quantum Design of Functional Materials(ICQD) University of Science and Technology of ChinaHefei 230026China CAS key laboratory of strongly coupled Quantum Matter physics Department of PhysicsUniversity of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China

Superconductors with reduced dimensionality have been widely explored for their exotic superconducting behaviors.Especially,at the two-dimensional limit,two-monolayer Pb films with two types of structures provide an ideal platform to unveil the underlying superconducting mechanism[Science 324,1314(2009)].Here,by combining scanning tunneling microscopy(STM)with the first-principle calculations,we successfully identify that these two types have different atomic lattice structures with varying stacking phases,which further enables us to calculate the phonon spectrum and electron phonon coupling strength of each type.The theoretical calculations are in good agreement with tunneling spectroscopy measurements of the superconducting transition temperatures(T_(c)),which established a correlation between atomic structures and superconductivity.Moreover,it was observed that the higher T_(c)of these two types also possess higher out-of-plane upper critical magnetic fields(Hc2).These findings will provide important new insights into two-dimensional superconductivity at the atomic level.

关键词： 2 ML Pb films superconductivity atomic structure scanning tunneling microscopy first-principle calculations

Localization effect in single crystal of RuAs2

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Chinese physics B 2024年第4期33卷 620-625页

作者：易哲铠刘琪光双魁徐升岳小宇梁慧李娜周颖吴丹丹孙燕李秋菊程鹏夏天龙孙学峰王义炎 Anhui key laboratory of Magnetic Functional Materials and Devices Institute of Physical Science and Information TechnologyAnhui University Department of physics and key laboratory of strongly-coupled Quantum Matter physics (CAS) University of Science and Technology of China Department of physics and Beijing key laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China School of Optical and Electronic Information Suzhou City University School of physics and Optoelectronic Engineering Anhui University Collaborative Innovation Center of Advanced Microstructures Nanjing University

We report the magnetotransport and thermal properties of RuAs2single crystal. RuAs2exhibits semiconductor behavior and localization effect. The crossover from normal state to diffusive transport in the weak localization（WL） state and then to variable range hopping（VRH） transport in the strong localization state has been observed. The transitions can be reflected in the measurement of resistivity and Seebeck coefficient. Negative magnetoresistance（NMR） emerges with the appearance of localization effect and is gradually suppressed in high magnetic field. The temperature dependent phase coherence length extracted from the fittings of NMR also indicates the transition from WL to VRH. The measurement of Hall effect reveals an anomaly of temperature dependent carrier concentration caused by localization effect. Our findings show that RuAs2is a suitable platform to study the localized state.

关键词： weak localization variable range hopping RuAs_2 single crystal

In situ generation of oxyanions-decorated cobalt(nickel)oxyhydroxide catalyst with high corrosion resistance for stable and efficient seawater oxidation

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Journal of Energy Chemistry 2024年第7期94卷 508-516页

作者： Fengting Luo Pei Yu Jueting Xiang Junjie Jiang Shijian Chen chongqing key laboratory of Interface physics in Energy Conversion College of PhysicsChongqing UniversityChongqing 401331China Center of Modern physics Institute for Smart City of Chongqing University in LiyangLiyang 213300JiangsuChina

The development of efficient and robust anode materials for stable alkaline seawater electrolysis is severely limited by chlorine evolution reaction and chloride corrosion.Here,the sulfur-doped cobalt-nickel bimetallic phosphides(CoNiPS)are specifically designed as a pre-catalyst for navigating a surface reconstruction to fabricate the anions(PO^(3-)_(4) and SO^(2-)_(4))-decorated Co(Ni)OOH catalyst(R-CoNiPS)with exceptional durability and high activity for stable alkaline seawater oxidation(ASO).Various experiment techniques together with theoretical simulations both demonstrate that the in situ-generated PO^(3-)_(4) and SO^(2-)_(4) anions on catalyst surface can improve the oxygen evolution reaction(OER)activity,regulating and stabilizing the catalytic active species Co(Ni)OOH,as well as make a critical role in inhibiting the adsorp-tion of chloride ions and extending the service life of electrode.Therefore,this R-CoNiPS electrode exhi-bits superb OER activity toward AsO and stands out among the non-precious ASO electrocatalysts reported recently,requiring low overpotentials of 420 and 440 mV to attain large current densities of 500 and 1000 mA cm^(-2) in an alkaline natural seawater electrolyte,respectively.Particularly,the catalyst displays a negligible chloride corrosion at room temperature during ASO operation(>200 h)at 500 mA cm^(-2).This work opens up a new viewpoint for designing high-activity and durable electrocata-lystsforseawaterelectrolysis.

关键词： Seawater electrolysis Anions Oxygen evolution reaction Chloride corrosion