Single-edge transport in an InAs/GaSb quantum spin Hall insulator

摘要

We report transport measurements in a single edge channel of an InAs/GaSbquantum spin Hall insulator, where the conduction occurs through only one pairof counterpropagating edge modes. By using a specific sample design involvinghighly asymmetric current paths, we electrically isolate a single edge channelof the two-dimensional topological insulator from the other edge. This enablesus to probe a single edge by multiterminal measurements. Both two-terminal andfour-terminal resistances show a nearly quantized plateau around $h/e^2$ for a4-$\mu$m-long edge, indicating quasiballistic transport. Our approach isadvantageous in that it allows us to gain insight into a microscopic regionfrom local measurements.