论文标题
拓扑磁电效应：非线性时间 - 反转对称响应，Witten效应和半级量子厅效应
Topological Magnetoelectric Effect: Nonlinear Time-Reversal-Symmetric Response, Witten Effect, and Half-Integer Quantum Hall Effect
论文作者
论文摘要
三个空间维度中的拓扑绝缘子（TIS）可以通过量化的磁电系数来表征。但是，这种耦合在存在时间反向对称性的情况下没有实验上可观察到的后果，因为批量和表面状态的贡献相互抵消。相反，Ti的特征响应是非线性磁电效应。讨论了非线性磁电响应的现场理论方面和实验相关几何的数值计算。与此效果不同的是，磁电耦合将响应单极，将电荷$ \ pm e/2 $结合，该单极被称为witten效果。如果时间逆转明确地通过作用在表面层上的采面田而破裂，则可以通过表面电子的半数量子霍尔效应来描述Ti的电磁响应。
Topological insulators (TIs) in three space dimensions can be characterized by a quantized magnetoelectric coefficient. However, this coupling does not have experimentally observable consequences in the presence of time-reversal symmetry, because the contributions of both bulk and surface states cancel each other. Instead, the characteristic response of a TI is a nonlinear magnetoelectric effect. Field theoretic aspects of the nonlinear magnetoelectric response and numerical calculations for experimentally relevant geometries are discussed. Distinct from this effect, the magnetoelectric coupling would bind a charge $\pm e/2$ in response to a monopole, which is referred to as Witten effect. If time reversal is broken explicitly, for instance, by a Zeeman field acting on the surface layer, the electromagnetic response of a TI can be described by a half-integer quantum Hall effect of surface electrons.
