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HL: Fachverband Halbleiterphysik

HL 30: Quantum transport and quantum Hall effects II (joint session HL/TT)

HL 30.3: Talk

Wednesday, March 29, 2023, 15:30–15:45, JAN 0027

Optical and electrical tuning between the normal insulating and topological insulating phase of InAs/GaSb bilayer quantum wells — •Manuel Meyer¹, Tobias Fähndrich¹, Sebastian Schmid¹, Sebastian Gebert¹, Gerald Bastard^1,2, Fabian Hartmann¹, and Sven Höfling¹ — ¹Technische Physik, Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Am Hubland, D-97074 Würzburg, Germany — ²Physics Department, École Normale Supérieure, PSL 24 rue Lhomond, 75005 Paris, France

Topological insulators (TI) based on InAs/GaSb bilayer quantum wells (BQW) are appealing due to their rich phase diagram with a TI and normal insulating (NI) phase[1]. The switching between both phases can be achieved by external electric fields using a top and back gate (TG and BG)[2]. However, especially a fully functional BG is difficult to realize in antimonides due to leakage issues. To overcome this bottleneck we present another tuning knob using optical excitation to switch from the NI to the TI phase over the TI gap[3]. By monitoring the charge carrier densities we can identify the hybridized band structure and in-plane magnetic field measurements evidence the TI gap. Furthermore, a top-gated sample is investigated. Without a back gate we find properties from both phases for magnetransport measurements which points to a mixing of NI and TI states. This is further indicated by the resistance peak evolutions with temperature for both samples.

[1] C. Liu et al., PRL 100, 236601 (2008)

[2] F. Qu et al., PRL 115, 036803 (2015)

[3] G. Knebl et al., PRB 98, 041301(R) (2018)