Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 29: Quantum Transport and Quantum Hall Effects
HL 29.4: Vortrag
Mittwoch, 20. März 2024, 10:30–10:45, EW 561
Anomalous conductance steps in 3DTI HgTe-based QPCs — •Elisabeth Richter1, Michael Barth2, Dmitriy Kozlov1, Juliane Steidl1, Klaus Richter2, and Dieter Weiss1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93053 Regensburg, Germany — 2Institut für Theoretische Physik, Universität Regensburg, 93053 Regensburg, Germany
Previously, 3DTI strained HgTe-based nanowires were studied in an axial magnetic field, exhibiting Aharonov-Bohm type oscillations [1]. Here, we study the conductance of short QPCs of different width and height in a perpendicular magnetic field. The QPCs are fabricated by lithography and etching, resulting in ballistic but non-adiabatic transport. Zero-field gate voltage traces show no quantisation and conductance in the range of 1 to 100 e2/h. In a quantising magnetic field, pronounced conductance plateaus are observed, coinciding with the position of the integer filling factors of the macroscopic part of the sample. Surprisingly, for narrow QPCs, the values of the plateaus are smaller than expected for the corresponding filling factors. Such behaviour could be considered as trivial impurity scattering; however, we found that certain conductance values are preferred over others. We hypothesise that the QPC acts as a kind of filter whose transmission depends on the structure of the energy bands in the QPC.
[1] Ziegler, J. et al., Phys. Rev. B 97, 035157 (2018)
Keywords: topological insulators; quantum point contacts; quantum transport; HgTe