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Enhanced and controllable reflected group delay based on Tamm surface plasmons with dirac semimetals

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Chinese Physics B 2023年第7期32卷 404-408页

作者：郑棋文卢文广胥加青叶云洋赵新民蒋乐勇 School of Physics and Electronics Hunan Normal UniversityChangsha 410081China School of Intelligent Manufacturing and Electronic Engineering Wenzhou University of TechnologyWenzhou 325035China School of Electronic Science and Engineering National University of Defense TechnologyChangsha 410073China

The reflected group delay from a multilayer structure comprising a one-dimensional photonic crystal coated with a bulk dirac semimetal(BDS)separated by a spacer layer is investigated *** is shown that the group delay of the reflected beam in this structure can be significantly negatively enhanced and switched from negative to *** enhanced group delay originates from the steep phase change caused by the excitation of the optical Tamm state at the interface between the BDS and spacer ***,positive and negative group delays can be actively tuned through the Fermi energy and the relaxation time of the *** believe that this enhanced and tunable delay scheme has important research significance for the fabrication of optical delay devices.

关键词： group delay Tamm plasmons dirac semimetals

Dynamic conductivity modified by impurity resonant states in doping three-dimensional dirac semimetals

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Frontiers of physics 2018年第2期13卷 175-183页

作者： Shuai Li Chen Wang Shi-Han Zheng Rui-Qiang Wang Jun Li Mou Yang Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China School of Information Engineering Guangdong University of Technology Guangzhou 510006 China

The impurity effect is studied in three-dimensional dirac semimetals in the framework of a T-matrix method to consider the multiple scattering events of dirac electrons off impurities. It has been found that a strong impurity potential can significantly restructure the energy dispersion and the density of states of dirac electrons. An impurity-induced resonant state emerges and significantly modifies the pristine optical response. It is shown that the impurity state disturbs the common longitudinal optical conductivity by creating either an optical conductivity peak or double absorption jumps, depending on the relative position of the impurity band and the Fermi level. More importantly, these conductivity features appear in the forbidden region between the Drude and interband transition, completely or partially filling the Pauli block region of optical response. The underlying physics is that the appearance of resonance states as well as the broadening of the bands leads to a more complicated selection rule for the optical transitions, making it possible to excite new electron-hole pairs in the forbidden region. These features in optical conductivity provide valuable information to understand the impurity behaviors in 3D dirac materials.

关键词： dirac semimetals impurity resonance states optical conductivity

Lattice thermal conduction in cadmium arsenide

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Chinese Physics B 2022年第11期31卷 424-430页

作者： R F Chinnappagoudra M D Kamatagi N R Patil N S Sankeshwar Department of Physics S.S.Government First Grade CollegeNargund-582207KarnatakaIndia Research Resource Centre Visvesvaraya Technological UniversityBelagavi-590018KarnatakIndia Department of Physics B V B College of Engineering and TechnologyHubliKarnataka 80031India Department of Physics&Electronics CHRIST(Deemed to be University)Bangalore-560029KarnatakaIndia

Lattice thermal conductivity(LTC)of cadmium arsenide(Cd_(3)As_(2))is studied over a wide temperature range(1–400 K)by employing the Callaway *** acoustic phonons are considered to be the major carriers of heat and to be scattered by the sample boundaries,disorder,impurities,and other phonons via both Umklapp and normal phonon *** calculations of LTC of Cd_(3)As_(2)bring out the relative importance of the scattering *** systematic analysis of recent experimental data on thermal conductivity(TC)of Cd_(3)As_(2)samples of different groups,presented in terms of LTC,κL,using a nonlinear regression method,reveals good fits to the TC data of the samples considered for T100 K the inclusion of the electronic component of TC,κe,incorporating contributions from relevant electron scattering mechanisms,is needed to obtain good agreement with the TC data over the wide temperature *** detailed investigations of TC of Cd_(3)As_(2)are required to better understand its suitability in thermoelectric and thermal management devices.

关键词： dirac semimetals Cd_(3)As_(2) thermal conductivity phonon scattering

A semiclassical approach to surface Fermi arcs in Weyl semimetals

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Science China(Physics,Mechanics & Astronomy) 2022年第6期65卷 110-115页

作者： Jiajia Huang Luyang Wang Dao-Xin Yao State Key Laboratory of Optoelectronic Materials and Technologies Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSchool of PhysicsSun Yat-sen UniversityGuangzhou 510275China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China International Quantum Academy Shenzhen 518048China

We present a semiclassical explanation for the morphology of the surface Fermi arcs of Weyl *** the surface states as a two-dimensional Fermi gas subject to band bending and Berry curvatures,we show that it is the non-parallelism between the velocity and the momentum that gives rise to the spiral structure of Fermi *** map out the Fermi arcs from the velocity field for a single Weyl point and a lattice with two Weyl *** also investigate the surface magnetoplasma of dirac semimetals in a magnetic field,and find that the drift motion,the chiral magnetic effect and the Imbert-Fedorov shift are all involved in the formation of surface Fermi *** work not only provides an insightful perspective on the surface Fermi arcs and a practical way to find the surface dispersion,but also paves the way for the study of other physical properties of the surface states of topological semimetals,such as transport properties and orbital magnetization,using semiclassical methods.

关键词： Weyl semimetals surface Fermi arcs semiclassical equations of motion dirac semimetals surface magnetoplasma

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