Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 29: Quantum Transport and Quantum Hall Effects

HL 29.7: Talk

Wednesday, March 20, 2024, 11:30–11:45, EW 561

Topological band structure of InAs/GaSb/InAs and InAs/GaInSb/InAs triple quantum wells — •Sebastian Gebert — Technische Physik, Physikalisches Institut, Am Hubland, D-97074 Würzburg, Germany

Going back to the initial proposal of Kane and Mele [1], the 2D topological insulator (TI) has attracted considerable attention. The first experimental demonstrations of such a TI phase were obtained in HgCdTe/HgTe/HgCdTe and InAs/GaSb quantum wells (QWs). In both cases the TI phase was restricted to cryogenic temperatures either by the strong temperature dependence of the bands or the inherently small bulk bandgap. A promising approach to overcome these limitations was proposed by Ref. [2]. They theoretically demonstrated, that by modifying the known InAs/GaSb QWs with an additional layer it is possible to realize a plethora of different phases, including a TI phase. More precisely, an InAs/GaSb/InAs TI could reach a bulk bandgap of 16 meV and a strained InAs/GaInSb/InAs TI up to 60mV. We here present gate voltage and temperature dependent magnetotransport measurements of InAs/GaSb/InAs and InAs/GaInSb/InAs QWs grown primarily in the TI phase. For later ones, we extract a bulk bandgap of 45 meV and the occuring edge conductivity, which persists up to 40 K, is attributed to the topological edge channels.

[1] C. L. Kane & E. J. Mele, Phys. Rev. Lett. 95, 146802

[2] S. S. Krishtopenko & F. Teppe, Science Advances Vol. 4, NO. 4

[3] C. Avogadri et al., Phys. Rev. Research 4, L042042

Keywords: Topological materials; Quantum spin Hall effect; Edge States