Magnetotransport on quantum spin Hall edge coupled to bulk midgap states
Magnetotransport on quantum spin Hall edge coupled to bulk midgap states
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DOI：
10.1103/physrevb.108.085436
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发表时间：
2023-02
影响因子：
3.7
通讯作者：
Y. Chen;Wenjing Zhao;E. Runburg;D. Cobden;D. Pesin
中科院分区：
文献类型：
--
作者：
Y. Chen;Wenjing Zhao;E. Runburg;D. Cobden;D. Pesin
我们考虑量子自旋霍尔绝缘体的螺旋边缘上的磁输运，在存在大量的midgap状态“侧耦合”的边缘。在磁场的存在下，带隙中的能级被自旋分裂，这些能级与巡回边缘态的杂交导致反向散射，并随之增加电阻。我们发现，有一个奇异的尖状贡献的正磁电阻产生的共振midgap状态弱耦合到边缘。奇异行为持续相干和非相干的边缘输运制度。我们使用发展的理论，以适应在液氦温度下的单层WTe$_2$的磁电阻的实验数据。拟合的结果表明，在具有长边沟道的WTe 2 $单层上实验观察到的弱磁场下的尖点电阻行为，确实可以用螺旋边态与自旋分裂的体中隙态的杂化来解释.特别是，外部磁场的方向上的磁阻的依赖性很好地描述了由非相干边缘传输理论，在同一时间是相当不同的一个预期的磁场诱导的边缘间隙。
We consider magnetotransport on a helical edge of a quantum spin Hall insulator, in the presence of bulk midgap states ``side-coupled"to the edge. In the presence of a magnetic field, the midgap levels are spin-split, and hybridization of these levels with the itinerant edge states leads to backscattering, and the ensuing increase in the resistance. We show that there is a singular cusp-like contribution to the positive magnetoresistance stemming from resonant midgap states weakly coupled to the edge. The singular behavior persists for both coherent and incoherent edge transport regimes. We use the developed theory to fit the experimental data for the magnetoresistance for monolayer WTe$_2$ at liquid helium temperatures. The results of the fitting suggest that the cusp-like behavior of the resistance in weak magnetic fields observed in experiments on monolayer WTe$_2$ with long edge channels might indeed be explained by hybridization of the helical edge states with spin-split bulk midgap states. In particular, the dependence of the magnetoresistance on the direction of the external magnetic field is well described by the incoherent edge transport theory, at the same time being quite distinct from the one expected for a magnetic-field-induced edge gap.