Quantum Hall effect and current distribution in the 3D topological insulator HgTe

TL;DR

This study investigates the quantum Hall effect in the 3D topological insulator HgTe, revealing that at high magnetic fields, multiple electronic subsystems merge, resulting in a uniform current distribution across the device.

Contribution

It provides experimental evidence of the merging of electronic subsystems and uniform current distribution in HgTe under high magnetic fields, using multiple measurement techniques.

Findings

Quantized Hall plateaus observed despite multiple carriers

Electronic subsystems merge at high magnetic fields

Current distributes across entire Hall bar at high fields

Abstract

We study the quantum Hall effect (QHE) in the three-dimensional topological insulator HgTe, which features topological Dirac-type surface states in a bulk gap opened by strain. Despite the co-existence of multiple carrier subsystems, the system exhibits perfectly quantized Hall plateaus at high magnetic fields. Here we study the system using three different experimental techniques: Transport experiments, capacitance measurements including the quantum capacitance, and current distribution measurements using electrostatically sensitive scanning probe microscopy. Our key finding is that at sufficiently high magnetic fields, the different electronic subsystems merge into one, and the current in a quantum Hall plateau is distributed across the entire width of the Hall bar device.