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Regensburg 2022 – scientific programme

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MA: Fachverband Magnetismus

MA 35: Poster 2

MA 35.74: Poster

Thursday, September 8, 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 κxx and thermal hall effect κxy data with the electrical counterparts (σxx & σxy), we study a possible influence of charge puddles on thermal transport. Electrical hall conductivity (σxy) 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 κe was calculated by using Wiedemann-Franz law and then compared with the measured thermal transport data where it was found that both κxx and κxy shows phonon dominated behaviour. When compared κxy and κe, data matches well with each other above 50K. In contrast, below 50K κxy shows a sign change and evolves to a large thermal hall signal, whereas κe 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)

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