Anomalous conductance steps in three-dimensional topological insulator HgTe-based quantum point contacts

TL;DR

This paper investigates unusual conductance steps in strained HgTe topological insulator quantum point contacts, revealing non-integer quantization under magnetic fields due to scattering effects, supported by numerical and phenomenological models.

Contribution

It demonstrates non-integer conductance quantization in HgTe topological insulator point contacts and attributes it to scattering effects, combining experimental observations with theoretical modeling.

Findings

Non-integer conductance steps observed at high magnetic fields

Scattering effects cause deviations from ideal quantization

Numerical and phenomenological models support experimental results

Abstract

We explore electrical transport through a point contact in strained HgTe, a three-dimensional topological insulator. In the absence of a magnetic field $B$, there is no quantization. However, under higher magnetic fields, we observe distinct non-integer conductance steps. Based on numerical tight-binding calculations and a phenomenological Landauer-B\"uttiker approach, we attribute these atypical, non-integer quantized plateaus to significant scattering effects at the point contact.