论文标题
在拓扑绝缘体的理论模型中，缺乏平衡边缘电流
Absence of equilibrium edge currents in theoretical models of topological insulators
论文作者
论文摘要
2D和3D拓扑绝缘子（TIS）的低能领域表现出传播的边缘状态，该状态猜测存在平衡边缘或边缘旋转电流。我们证明，如果以直接的方式将TIS的低能领域正规化为正方形或立方晶格，则实际上，来自边缘状态的电流被从价带中完全取消，从而使得没有边缘电流。该结果警告说，对于拓扑绝缘体的任何平衡特性，价带的贡献不应忽略。在这些正规晶格模型中，仅当边缘状态的狄拉克点从化学势转移时，才有有限的边缘电流，例如，通过掺杂，杂质，边缘限制电势，表面带弯曲或栅极电压。量化小量子点中的边缘电流，量化栅极电压的函数，边缘电流可以从门控区域流出到边缘状态的衰减长度。
The low energy sector of 2D and 3D topological insulators (TIs) exhibits propagating edge states, which has speculated the existence of equilibrium edge currents or edge spin currents. We demonstrate that if the low energy sector of TIs is regularized in a straightforward manner into a square or cubic lattice, then the current from the edge states is in fact canceled out exactly by that from the valence bands, rendering no edge current. This result serves as a warning that for any equilibrium property of topological insulators, the contribution from the valence bands should not be overlooked. In these regularized lattice model, there is a finite edge current only if the Dirac point of the edge states is shifted away from the chemical potential, for instance by doping, impurities, edge confining potential, surface band bending, or gate voltage. The edge current in small quantum dots as a function of the gate voltage is quantized, and the edge current can flow out of the gated region up to the decay length of the edge state.
