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

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-Büttiker approach, we attribute these atypical, non-integer quantized plateaus to significant scattering effects at the point contact.