SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 41: Quantum Transport and Quantum Hall Effects II (joint session HL/TT)
TT 41.4: Vortrag
Mittwoch, 29. März 2023, 16:15–16:30, JAN 0027
Transport in high mobility HgTe heterostructures — •Michael Kick, Lena Fürsst, Johannes Kleinlein, Saquib Shamim, Hartmut Buhmann, and Laurens W. Molenkamp — Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
The Fractional Quantum Hall Effect (FQHE) has not yet been observed in the material system of HgTe. Due to recent progress in MBE growth, routinely charge carrier mobilities of HgTe heterostructures of over µ > 1· 106 cm2/Vs are obtained which is in the same order of magnitude as in the first reported experimental observation of the FQHE in GaAs/GaAlAs heterostructures. This opens up new prospects for transport investigations into the long time still open question of fractional states in this material system.
In 2-dimensional HgTe quantum wells, transport measurements show well pronounced quantum Hall plateaus for all filling factors, but no indication of any fractional state. High magnetic field measurements show a prolonged ν=1 plateau and a transition to an insulating state. Intriguingly, the ν=1 plateau exhibits a transition to an insulating state for filling factor ν=1/2.
Another possibility to observe the FQHE in HgTe is provided by the 2D surface states of a 3D topological insulator. High mobility layers, µ > 1· 106 cm2/Vs, of tensil strained HgTe are subject of extensive magneto-transport investigations. First results reveal a good and detailed correspondence to recent k.p band structure calculations for non-interacting electron systems.