Shekhar, Chandra
Chandra Shekhar
Group leader
Phone: +49 351 4646-3205

Topological Materials

Publication highlights

Chandra Shekhar, C. E. ViolBarbosa, Binghai Yan, Siham Ouardi, W. Schnelle, Gerhard H. Fecher, and Claudia Felser, "Evidence of surface transport and weak antilocalization in a single crystal of the Bi2Te2Se topological insulator," Physical Review B 90 (16), 1-6 (2014).
C. Shekhar, S. Ouardi, A. K. Nayak, G. H. Fecher, W. Schnelle, and C. Felser, "Ultrahigh mobility and nonsaturating magnetoresistance in Heusler topological insulators," Physical Review B 86 (15), 155314-1-155314-5 (2012).

Topological Insulators: Probing the surface states

In three-dimensional (3D) TIs, topological surface states have been successfully investigated by surface-sensitive techniques such as angle-resolved photoemission spectroscopy. However, finding evidence of transport through the surface states by regular transport measurements remains a challenge owing to the presence of parallel bulk conducting channels that usually dominate the transport properties. We explored these surface states by measuring the four-probe resistance in a special geometry, putting the voltage and current contacts at unusual positions. Our results show a crossover from bulk to surface conduction below 20 K in Bi2Te2Se. Besides this, the magnetoconductance provides clear evidence of weak anti-localization, which also indicates a strong contribution of topological surface states.

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