Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Poster 2

MA 35.74: Poster

Donnerstag, 8. September 2022, 16:00–18:00, P4

Electrical and thermal hall transport in compensated topological insulator BiSbTeSe₂ — •Rohit Sharma, Mahasweta Bagchi, Oliver Breunig, Yoichi Ando, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany

The existence of puddles in BiSbTeSe₂ at low temperature (T < 50K) has been detected using optical conductivity measurements, where DC electrical conductivity data shows an insulating behaviour, but above 50K, optical and transport results agree well with each other due to evaporation of charge puddles with increasing T[1]. By comparing thermal conductivity κ_xx and thermal hall effect κ_xy data with the electrical counterparts (σ_xx & σ_xy), we study a possible influence of charge puddles on thermal transport. Electrical hall conductivity (σ_xy) shows hole like (p-type) behaviour at elevated T, which changes to multi-band behaviour at low T. From the electrical transport data electronic contribution to thermal transport κ_e was calculated by using Wiedemann-Franz law and then compared with the measured thermal transport data where it was found that both κ_xx and κ_xy shows phonon dominated behaviour. When compared κ_xy and κ_e, data matches well with each other above 50K. In contrast, below 50K κ_xy shows a sign change and evolves to a large thermal hall signal, whereas κ_e has no sign change and smoothly decreases. Possible reason for large thermal hall effect in BiSbTeSe₂ will be discussed.
Funded by the DFG via CRC 1238 Projects A04 and B01
[1] N. Borgwardt et al. Phys. Rev. B. 93, 245149 (2016)