Non-local transport via edge-states in InAs/GaSb coupled quantum wells

TL;DR

This study investigates edge-state transport in InAs/GaSb quantum wells, revealing non-quantized resistance plateaus and non-local edge conduction, influenced by edge imperfections and residual bulk conductivity.

Contribution

It provides experimental insights into non-local edge transport and resistance behavior in InAs/GaSb quantum wells near the topological phase transition.

Findings

Observation of resistance plateaus near charge neutrality

Detection of non-local edge transport signals

Resistance values deviate from ideal quantized levels

Abstract

We have investigated low-temperature electronic transport on InAs/GaSb double quantum wells, a system which promises to be electrically tunable from a normal to a topological insulator. Hall bars of $50\,\mu$m in length down to a few $\mu$m gradually develop a pronounced resistance plateau near charge-neutrality, which comes along with distinct non-local transport along the edges. Plateau resistances are found to be above or below the quantized value expected for helical edge channels. We discuss these results based on the interplay between imperfect edges and residual local bulk conductivity.