论文标题
超低载流子密度拓扑隔绝缘子的双极磁光响应
Ambipolar magneto-optical response of ultra-low carrier density topological insulators
论文作者
论文摘要
我们已经研究了使用时间域THZ Polarimetry的SB $ _2 $ _2 $ TE $ _3 $的THZ范围磁光响应。未掺杂的SB $ _2 $ TE $ _3 $具有散装价带内的化学潜力。因此，其拓扑响应被散装载体掩盖。但是，使用适当的缓冲层工程和化学掺杂，SB $ _2 $ te $ _3 $薄膜可以使用极低的电子或孔密度生长。在存在磁场的情况下，超低载体密度样品显示出异常的光学特性和量化响应。与对狄拉克费米斯的期望一致，即使在零场电导率低于可检测水平的样品中，也可以看到量化的大厅响应。在法拉第角的不连续性在零范围内的填充分数发生较小的变化是2D迪拉克系统中平均异常的表现，其时间反向对称性断裂。
We have investigated the THz range magneto-optical response of ultralow carrier density films of Sb$_2$Te$_3$ using time-domain THz polarimetry. Undoped Sb$_2$Te$_3$ has a chemical potential that lies inside the bulk valence band. Thus its topological response is masked by bulk carriers. However, with appropriate buffer layer engineering and chemical doping, Sb$_2$Te$_3$ thin films can be grown with extremely low electron or hole densities. The ultralow carrier density samples show unusual optical properties and quantized response in the presence of magnetic fields. Consistent with the expectations for Dirac fermions, a quantized Hall response is seen even in samples where the zero field conductivity falls below detectable levels. The discontinuity in the Faraday angle with small changes in the filling fraction across zero is manifestation of the parity anomaly in 2D Dirac systems with broken time reversal symmetry.
