Two-dimensional topological insulators can feature one-dimensional charge transport via edge modes, which offer a rich ground for studying exotic quasi-particles and for quantum materials applications. In this work, we use lateral junction devices, defined by nanoscale finger gates, to study edge mode transport in the two-dimensional topological insulator Cd₃As₂. The finger gate can be tuned to transmit an integer number of quantum Hall edge modes and exhibits full equilibration in the bipolar regime. When the Fermi level of the channel crosses a Landau level, reflected modes percolate through the channel, resulting in an anomalous conductance peak. The device does not fully pinch off when the channel is tuned into the topological gap, which is a sign of remnant modes in the channel. These modes are expected from band inversion, while residual bulk conduction associated with the disorder potential may also play a role.

二维拓扑绝缘体可以通过边缘模式实现一维电荷传输，这为研究奇异的准粒子和量子材料应用提供了丰富的基础。在这项工作中，我们使用由纳米级指栅定义的横向结器件来研究二维拓扑绝缘体 Cd ₃ As ₂中的边缘模式传输。手指门可以调节以传输整数个量子霍尔边缘模式，并在双极状态下表现出完全平衡。当通道的费米能级穿过朗道能级时，反射模式渗透通过通道，导致反常电导峰值。当通道调谐到拓扑间隙时，器件不会完全夹断，这是通道中剩余模式的标志。这些模式是能带反转所预期的，而与无序电势相关的残余体传导也可能发挥作用。