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

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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 noninteger conductance steps. Based on numerical tight-binding calculations and a phenomenological Landauer-Büttiker approach, we attribute these atypical, noninteger quantized plateaus to significant scattering effects at the point contact.