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

作　　者：Shuai Li Chen Wang Shi-Han Zheng Rui-Qiang Wang Jun Li Mou Yang 

机构地区：[1]Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China [2]School of Information Engineering, Guangdong University of Technology, Guangzhou 510006, China

出　　处：《Frontiers of physics》2018年第2期175-183,共9页物理学前沿（英文版）

基　　金：This work was supported by Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme （CDUPS） （2017）, the National Natural Science Founda-tion of China （Grant Nos. 11474106 and 11774100）, Guangdong Natural Science Foundation of China （Grant Nos. 2017B030311003 and 2015A030313384）, and the Innovation Project of Graduate School of South China Normal University.

摘　　要：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.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 

分 类 号：O562.2[理学—原子与分子物理] TN304.12[理学—物理]