电子-杂质和电子-声子相互作用对石墨烯磁光导的影响

在外加垂直磁场的石墨烯系统中,基于格林函数方法以自能的形式理论研究了电荷杂质散射和光学声子散射中心对朗道能谱的影响,采用久保(Kubo)公式研究了单层石墨烯的磁光电导谱以及跃迁选择定则。具体计算中电子-杂质库仑相互作用考虑了介电环境的屏蔽效应,对由散射引起的自能以及单粒子格林函数做自洽计算,另外在强磁场下单杂质散射是一个很好的近似模型。理论计算结果表明电荷杂质散射引起朗道能级对称展宽;同时考虑电荷杂质和光学声子两类散射后态密度表现为非对称的展宽。研究结果表明磁光电导谱的峰值和强度强烈依赖于填充因子和态密度。

Magneto-Otical Conductivity Induced by Electron-Impurity and Electron-Phonon Interaction in Graphene

A theoretical study on the optical conductivity in the presence of perpendicular magnetic fields and scattering centers such as charged impurities and optical phonons in graphene is presented. The standard Kubo formula is employed to evaluate the magneto-optical conductivity. The screaning effect of the dielectric environment is included in the calculation of the electron-impurity interation and the self-energy induced by impurity and optic-phonon scattering and the Green′s function for a carrier are calculated self-consistently. In a strong magnetic field, the single impurity scattering is a good approximation. It is found that the charged impurity scattering results in a symmetric Landau level broadening while the combined charged impurity and optical phonon scattering can lead to an asymmetric broadening of density of states (DOS). The peak position and intensity of the magneto-optical conductivity depend strongly on the filling factor and the broadened DOS.