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Phonon transport properties of Janus Pb_(2)XAs(X=P,Sb,and Bi)monolayers:A DFT study

Chinese Physics B 2024年第4期33卷 71-76页

作者：耿嘉鑫张培汤准韵欧阳滔 School of Physics and Optoelectronics and Hunan Key Laboratory for Micro-Nano Energy Materials and Device Xiangtan UniversityXiangtan 411105China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China

Grasping the underlying mechanisms behind the low lattice thermal conductivity of materials is essential for the efficient design and development of high-performance thermoelectric materials and thermal barrier coating *** this paper,we present a first-principles calculations of the phonon transport properties of Janus Pb_(2)PAs and Pb_(2)SbAs *** materials possess low lattice thermal conductivity,at least two orders of magnitude lower than graphene and *** room temperature thermal conductivity of Pb_(2)SbAs(0.91 W/m K)is only a quarter of that of Pb_(2)PAs(3.88 W/m K).We analyze in depth the bonding,lattice dynamics,and phonon mode level information of these ***,it is determined that the synergistic effect of low group velocity due to weak bonding and strong phonon anharmonicity is the fundamental cause of the intrinsic low thermal conductivity in these Janus *** regular residual analysis further indicates that the four-phonon processes are limited in Pb_(2)PAs and Pb_(2)SbAs,and the three-phonon scattering is sufficient to describe their *** this study,the thermal transport properties of Janus Pb_(2)PAs and Pb_(2)SbAs monolayers are illuminated based on fundamental physical mechanisms,and the low lattice thermal conductivity endows them with the potential applications in the field of thermal barriers and thermoelectrics.

关键词： lattice thermal conductivity weak bonding phonon anharmonicity first principles calculations

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Parameter estimation in n-dimensional massless scalar field

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Chinese Physics B 2024年第3期33卷 231-237页

作者：杨颖荆继良 Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Educationand Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081Chin

Quantum Fisher information(QFI)associated with local metrology has been used to parameter estimation in open quantum *** this work,we calculated the QFI for a moving Unruh-DeWitt detector coupled with massless scalar fields in n-dimensional spacetime,and analyzed the behavior of QFI with various parameters,such as the dimension of spacetime,evolution time,and Unruh *** discovered that the QFI of state parameter decreases monotonically from 1 to 0 over ***,we noted that the QFI for small evolution times is several orders of magnitude higher than the QFI for long evolution *** also found that the value of QFI decreases at first and then stabilizes as the Unruh temperature *** was observed that the QFI depends on initial state parameterθ,and Fθis the maximum forθ=0 orθ=π,Fφis the maximum forθ=π/*** also obtain that the maximum value of QFI for state parameters varies for different spacetime dimensions with the same evolution time.

关键词： quantum Fisher information parameter estimation open quantum systems

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Magnetic triple Weyl semimetals that are robust against spin-orbit coupling

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Physical Review B 2024年第14期110卷 L140409页

作者： Guang Liu Peiyao Qin Jun Ren Zhongjia Chen Guanghui Zhou Hu Xu Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronics Department of Physics Dongguan Guangdong 523808 People's Republic of China Deparment of Physics (Guangdong) Shenzhen 518045 People's Republic of China

Magnetic order, when coupled with band topology, gives rise to diverse magnetic topological phases. In this study, we focus on space group 173, particularly emphasizing the out-of-plane ferromagnetic order, to analyze how magnetic order and spin-orbit coupling (SOC) influence band symmetry changes. Our first-principles calculations and symmetry analysis predict that ferromagnetic La3AlCrS7 is an ideal candidate for the triple Weyl semimetal. In the absence of SOC, the spin-majority bands are conductive while the spin-minority bands are insulating, resulting in a fully polarized Weyl semimetal. Furthermore, within the framework of spin group theory, the triple hourglass Weyl point is stabilized by both C6 screw rotation symmetry and a redefined time-reversal symmetry. Remarkably, this triple Weyl point remains robust against SOC, and the topological sextuple-helicoid surface states are clearly visible regardless of the presence of SOC. This study not only provides a promising platform for the experimental observation of triple Weyl fermions, but also opens avenues for exploring unprecedented phenomena in triple Weyl semimetals.

关键词： Ferromagnetism Symmetry protected topological states Weyl fermions Weyl semimetal First-principles calculations k dot p method

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The comparison of manganese spectral lines for self-absorption reduction in LIBS using laser-induced fluorescence

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Plasma Science and Technology 2023年第6期25卷 82-87页

作者：唐云李菁锋马世祥胡桢麟彭旭翔周伟平袁晓沈萌 Hunan Province Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronic ScienceHunan University of Science and TechnologyXiangtan 411201People's Republic of China National Engineering Research Center of Intelligent Equipment for Agriculture Beijing Academy of Agriculture and Forestry SciencesBeijing 100097People's Republic of China Wuhan National Laboratory for Optoelectronics(WNLO) Huazhong University of Science and TechnologyWuhan 430074People's Republic of China

The detection of manganese(Mn)in steel by laser-induced breakdown spectroscopy(LIBS)provides essential information for ***,self-absorption greatly disrupts the LIBS spectral lines of Mn with high *** this study,to minimize self-absorption for Mn spectral lines in LIBS,laser-induced fluorescence(LIF)was *** with conventional LIBS,the self-absorption factors(α)of Mn I 403.08,403.31,and 403.45 nm lines were reduced by 90%,88%,and 88%,respectively;the root mean square errors of crossvalidation were decreased by 88%,85%,and 87%,respectively;the average relative errors were reduced by 93%,90%,and 91%,respectively;and average relative standard deviations were decreased by 29%,32%,and 33%,*** LIBS-LIF was shown to successfully minimize the self-absorption effect and spectral intensity fluctuation and improve detection accuracy.

关键词： laser-induced breakdown spectroscopy self-absorption LIBS-LIF

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Light-induced anomalous Hall, Nernst, and thermal Hall effects in black phosphorus thin films

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Physical Review B 2024年第12期110卷 125411页

作者： Benliang Zhou Rongfang Zeng Benhu Zhou Xiaoying Zhou Kaike Yang Guanghui Zhou Department of Physics Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan Province Department of Physics School of Physics and Electronics Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials

Light irradiation is a common and flexible method to induce Berry curvature in low-dimensional materials by breaking time-reversal symmetry. The recent Floquet band engineering in black phosphorus (BP) was successfully realized in experiment [S. Zhou et al., Nature (London) 614, 75 (2023)], hereby, we study the anomalous Hall, Nernst, and thermal Hall effects in BP thin films irradiated by an off-resonant circularly polarized light. Using the k·p Hamiltonian and Floquet theory, we derive the effective Hamiltonian and Berry curvature through two-photon processes up to the second order. We find that the light slightly increases the band gap, and the Berry curvature increases with increasing light intensity. Notably, the anomalous Hall conductivity exhibits a negative plateau width equal to the band gap, which is four orders of magnitude larger than that of monolayer BP. On the contrary, the anomalous Nernst conductivity is always zero within the band gap, showing a dip-peak profile. The anomalous thermal Hall conductivity trend mirrors that of the anomalous Hall conductivity, in line with the Wiedemann-Franz law. Our results provide a feasible method to obtain a finite Berry curvature and shed light on possible topological phase in BP thin films.

关键词： Electrical conductivity Electrical properties Electronic structure Optical conductivity Thermoelectric effects 2-dimensional systems Graphene Nanostructures Phosphorene Silicene Thin films Band structure methods Density functional theory Green's function methods Tight-binding model k dot p method

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Mapping the antiparallel aligned domain rotation by microwave excitation

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Chinese Physics B 2024年第9期33卷 599-605页

作者： Jing Zhang Yuanzhi Cui Xiaoyu Wang Chuang Wang Mengchen Liu Jie Xu Kai Li Yunhe Zhao Zhenyan Lu Lining Pan Chendong Jin Qingfang Liu Jianbo Wang Derang Cao College of Physics Qingdao UniversityQingdao 266071China National Demonstration Center for Experimental Applied Physics Education Qingdao UniversityQingdao 266071China SKLSM Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Chemistry Chemical Engineering and Resource UtilizationNortheast Forestry UniversityHarbin 150040China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China CAS Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Key Laboratory of Optic-Electronic Information and Materials of Hebei Province Research Center for Computational PhysicsCollege of Physics Science and TechnologyHebei UniversityBaoding 071002China Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education Lanzhou UniversityLanzhou 730000China Key Laboratory of Special Functional Materials and Structural Design Ministry of EducationLanzhou UniversityLanzhou 730000China

The evolution process of magnetic domains in response to external fields is crucial for the modern understanding and application of *** this study,we investigated the domain rotation in stripe domain films of varying thicknesses by examining their response to microwave excitation in four different *** resonance spectra indicate that the rotation field of stripe domain film under an applied magnetic field approaches the field where the resonance mode of sample *** saturation field of the stripe domain film corresponds to the field where the resonance mode disappears when measured in the stripe direction parallel to the microwave magnetic *** results are reproducible and consistent with micromagnetic simulations,providing additional approaches and techniques for comprehending the microscopic mechanisms of magnetic domains and characterizing their rotation.

关键词： stripe domain magnetic film microwave excitation micromagnetic simulation

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采用丁二腈拓宽Li/CFx一次电池的使用温度范围

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Journal of Central South University 2023年第2期30卷 443-453页

作者：王宁罗振亚张庆丰潘俊安袁铜杨颖谢淑红 Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials Department of PhysicsHunan University of Science and TechnologyXiangtan 411201China

在锂离子一次电池中,氟化碳(CFx)正极因具备高能量密度而广受关注。然而,低温下CFx正极的放电比容量急剧衰减。本研究采用丁二腈(SN)作为电解液添加剂,提高了-20℃~60℃宽温范围内的放电性能。实验结果表明,以0.5C倍率放电时,60℃、40℃... 详细信息

在锂离子一次电池中,氟化碳(CFx)正极因具备高能量密度而广受关注。然而,低温下CFx正极的放电比容量急剧衰减。本研究采用丁二腈(SN)作为电解液添加剂,提高了-20℃~60℃宽温范围内的放电性能。实验结果表明,以0.5C倍率放电时,60℃、40℃、25℃、0℃、-10℃和-20℃的放电比容量分别是869.9 mA·h/g、801.9 mA·h/g、761.8 mA·h/g、527.3 mA·h/g、299.4 mA·h/g、140.7 mA·h/g,明显高于无添加剂的放电比容量792 mA·h/g、766.6 mA·h/g、723.6 mA·h/g、398.8 mA·h/g、207 mA·h/g、137.7 mA·h/g。由于丁二腈参与了固体电解质中间相的形成,有效地降低了电化学阻抗,加快了放电反应动力学,改善了电池的低温电化学性能。同时,SN改善了低温下电解液与隔膜之间的相容性,提高了Li+的迁移扩散速率。本研究提供了一种方便、低黏度的电解液体系,拓宽了Li/CFx一次电池在宽温域下的应用。

关键词： Li/CFx一次电池丁二腈电解液宽温域放电比容量

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Impurity scattering and Friedel oscillations in altermagnets

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Physical Review B 2024年第16期110卷 165413页

作者： Wang Chen Xiaoying Zhou Dong Zhang Ying-Qiang Xu Wen-Kai Lou SKLSM College of Materials Science and Opto-electronic Technology Center of Materials Science and Optoelectronics Engineering Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronics Science

Altermagnetism is a newly predicted type of magnetism with spin-polarized electron bands but zero net magnetization. Here, we investigate the impurity scattering effect in an altermagnetic metal by using the T−matrix approach. We first calculate the impurity-induced local density of states (LDOS) in momentum space for a single scalar/magnetic impurity. In the absence (presence) of spin-orbit coupling and Zeeman field, the LDOS exhibits (does not exhibit) C4 symmetry due to the d−wave nature of the Fermi surfaces. In real space, we obtain the analytical expressions for the Friedel oscillation of LDOS based on the k·p Hamiltonian. The behavior of LDOS oscillations without spin-orbit coupling and Zeeman field also shows C4 symmetry. The amplitude of the LDOS decreases with r−1 in all directions at long distances, which is the same as that in conventional metals since they both have parabolic dispersion. However, the period of Friedel oscillations in an altermagnet is strongly anisotropic and depends on the direction of observation. Specifically, along the direction with (without) the spin splitting of the Fermi surface, the oscillation periods of the spin-up and spin-down LDOS are different (identical), resulting in an unfixed (a fixed) period at a given energy for the total LDOS. The difference between the two periods is proportional to the magnitude of the spin splitting of the Fermi surface. Our results reveal unique and universal features of the Fermi surfaces of an altermagnet that can be tested by spin-polarized scanning tunneling microscopy.

关键词： Altermagnetism Fermi surface Local density of states Quantum interference effects Green's function methods Surface scattering k dot p method

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Polarization-modulating switchable and selectable image display through an ultrathin quasi-bound-state-in-the-continuum metasurface

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Physical Review Applied 2024年第3期21卷 034039-034039页

作者： Zonglin Li Guozheng Nie Junhui Wang Fang Zhong Shiping Zhan School of Physics and Electronic Science Hunan University of Science and Technology Xiangtan Hunan 411201 China Hunan Provincial Key Laboratory of Intelligent Sensors and New Sensor Materials Xiangtan Hunan 411201 China

Active manipulation on absorption takes an essential place in nanophotonic light modulators, which always suffer from static tuning ability, limited depth, and insufficient modulating efficiency. In this study, we propose an alternative strategy utilizing the symmetry-protected-type bound state in the continuum (SPBIC) to satisfy a tunable critical-coupling absorber with high modulating mobility. To demonstrate our concept, we illustrate an ultrathin critical-coupling absorbing system composed of germanium metasurface and monolayer graphene through elaborately maneuvered quasi-SPBIC, which provides substantial local field enhancement to boost the light absorption of graphene. The intensity of such critical-coupling absorption can be efficiently tuned by modulating the polarization of the incident waves with an efficiency of 97.1%. Via this polarization control, we demonstrate digital switch “0-1” and switchable and selectable image-displaying functions in simulation. Such functions are obtained in one single-designed array by incident polarization while requiring no additional structural change. Our results may pave the way for next-gen nanophotonic metadevices.

关键词： Bound states in the continuum Fano resonance Imaging & optical processing Nanophotonics Polarization of light Graphene Metamaterials Metasurfaces

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Antisymmetry-breaking-coupling–enhanced sensing of quantum reservoirs

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Physical Review A 2024年第1期110卷 012613-012613页

作者： Ji-Bing Yuan Zhi-Min Tang Ya-Ju Song Shi-Qing Tang Zhao-Hui Peng Xin-Wen Wang Le-Man Kuang Key Laboratory of Opto-electronic Control and Detection Technology of University of Hunan Province and College of Physics and Electronic Engineering Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials and Department of Physics Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education and Department of Physics Synergetic Innovation Academy for Quantum Science and Technology

We investigate the use of a single generalized dephasing qubit for sensing a quantum reservoir, where the antisymmetry of the coupling between the qubit and its reservoir is broken. Our results indicate that, in addition to the decay factor encoding channel, the antisymmetry breaking coupling introduces another phase factor encoding channel. We propose an optimal measurement strategy for the generalized dephasing qubit, which enables the practical measurement precision to reach the theoretical ultimate precision quantified by the quantum signal-to-noise ratio (QSNR). As an application example, the generalized dephasing qubit is employed to estimate the s-wave scattering length of an atomic Bose-Einstein condensate. It is found that the QSNR contributed by the antisymmetry breaking coupling is at least two orders of magnitude higher than the QSNR contributed by the antisymmetry coupling at the millisecond timescale, and the optimal relative error can achieve a scaling ∝1/(χt) in long-term encoding, where χ represents the relative driving strength and t is the encoding time. Our work opens a way for supersensitive sensing of quantum reservoirs.

关键词： Open quantum systems & decoherence Quantum parameter estimation Bose-Einstein condensates

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