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TT: Fachverband Tiefe Temperaturen

TT 28: Poster Session: Topological Topics

TT 28.6: Poster

Montag, 12. März 2018, 15:00–19:00, Poster B

Giant microwave magneto-conductivity in topological Insulators — •Lea Pitz-Paal, Mahasweta Bagchi, Christoph Grams, Zhiwei Wang, Yoichi Ando, and Joachim Hemberger — Universität zu Köln

Recently, locally conducting puddles were identified in the bulk-insulating topological insulator BiSbTeSe₂ at temperatures below 50K [1]. These puddles are the result of imperfect compensation of charged donors and acceptors in the bulk. Additionally, it was shown that these puddles in a nearly bulk-insulating topological insulator TlBi_0.15Sb_0.85Te₂ grow in an increasing magnetic field [2]. This was detected when observing the resulting enhancement of the DC-conductivity. The puddles are growing due to the magnetic field and therefore form a percolating current paths. In the case of BiSbTeSe₂ the puddles are not connected because of much better compensation. Therefore, an enhancement of the puddles size is not observable with DC-measurements in this case. Hence, to examine the puddles in BiSbTeSe₂, an alternative approach based on AC-measurements in magnetic field is presented here. Our measurement also show an considerably enhanced AC-conductivity with increasing magnetic field and, therefore, a growth of the puddles.

This work is supported by the DFG via SFB1238 (Cologne).
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O. Breunig et al., Nat. Commun. 8, 15545(2017)