Contact

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

Topological Materials

Publication highlights

1.
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).
2.
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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