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arXiv 1703.00510cond-mat.str-elcond-mat.mes-hall
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强光场中的动力学量子反常霍尔效应

Dynamical Quantum Anomalous Hall Effect in Strong Optical Fields

Woo-Ram Lee, Wang-Kong Tse

摘要:

拓扑绝缘体在时间反演对称性破缺时,其表面拓扑态会产生量子反常霍尔效应。最近的磁光效应引起的QAHE实验的启发,我们开发了一个理论的动态霍尔电导率的亚隙光频率和强光场使用Keldysh-Floquet格林函数形式主义。我们的理论揭示了一个非线性制度,其中霍尔电导率保持接近$e^2/2h$在低频。在更高的光场,我们发现,随后的崩溃的半量子化伴随着相干振荡的动态霍尔电导率作为场强的函数,触发形成的Floquet子带和伴随的子带间跃迁。

英文摘要:

Topological insulators (TIs) are characterized by the quantum anomalous Hall effect (QAHE) on the topological surface states under time-reversal symmetry breaking. Motivated by recent experiments on the magneto-optical effects induced by the QAHE, we develop a theory for the dynamical Hall conductivity for subgap optical frequency and intense optical fields using the Keldysh-Floquet Green's function formalism. Our theory reveals a nonlinear regime in which the Hall conductivity remains close to $e^2/2h$ at low frequencies. At higher optical fields, we find that the subsequent collapse of the half quantization is accompanied by coherent oscillations of the dynamical Hall conductivity as a function of field strength, triggered by the formation of Floquet subbands and the concomitant inter-subband transitions.

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