论文标题

三角翘曲对异常材料的光学特性的影响

Trigonal warping effects on optical properties of anomalous Hall materials

论文作者

Adhidewata, Jyesta M., Komalig, Ravanny W. M., Ukhtary, M. Shoufie, Nugraha, Ahmad R. T., Gunara, Bobby E., Hasdeo, Eddwi H.

论文摘要

拓扑绝缘子的拓扑性质与材料中存在的对称性有关,例如,在拓扑绝缘子中可以观察到具有时间逆转对称性的量子旋转霍尔效应,而破裂的时间逆转对称性可能会导致异常量子霍尔效应(AHE)的存在。在这里,我们考虑了破裂的旋转对称性对AHE材料的Dirac锥的影响,通过向Dirac Hamiltonian添加三角形翘曲术语。我们以半分析来计算线性光学电导率,以说明如何通过打破旋转对称性,我们可以获得拓扑上不同的相。添加三角形翘曲术语会导致出现额外的狄拉克锥,当合并时,总的Chern总数为$ \ mp 1 $,而不是$ \ pm 1/2 $。这会导致异常大厅和纵向电导率的急剧变化。三角翘曲术语还激活了$ \ Mathcal {r} $对称的常规迪拉克材料中不存在的高级大厅响应。我们发现即使没有浆果曲率偶极子,也存在非零二阶霍尔电流。这种偏移电流也不受狄拉克锥体的手性影响,这应该导致时间反向对称系统中的非零霍尔电流。

The topological nature of topological insulators are related to the symmetries present in the material, for example, quantum spin Hall effect can be observed in topological insulators with time reversal symmetry, while broken time reversal symmetry may give rise to the presence of anomalous quantum Hall effect (AHE). Here we consider the effects of broken rotational symmetry on the Dirac cone of an AHE material by adding trigonal warping terms to the Dirac Hamiltonian. We calculate the linear optical conductivity semi-analytically to show how by breaking the rotational symmetry we can obtain a topologically distinct phase. The addition of trigonal warping terms causes the emergence of additional Dirac cones, which when combined has a total Chern number of $\mp 1$ instead of $\pm 1/2$. This results in drastic changes in the anomalous Hall and longitudinal conductivity. The trigonal warping terms also activates the higher order Hall responses which does not exist in a $\mathcal{R}$ symmetric conventional Dirac material. We found the presence of a non-zero second order Hall current even in the absence of Berry curvature dipole. This shift current is also unaffected by the chirality of the Dirac cone, which should lead to a non-zero Hall current in time reversal symmetric systems.

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