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Phys Rev Lett. 2015 Mar 6;114(9):096601. Epub 2015 Mar 3.

Tuning bulk and surface conduction in the proposed topological Kondo insulator SmB(6).

Author information

1
Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
2
Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA.
3
School of Physics, Monash University, Melbourne, Victoria 3800, Australia.
4
Canadian Institute for Advanced Research, Toronto, Canada M5G 1Z8.

Abstract

Bulk and surface state contributions to the electrical resistance of single-crystal samples of the topological Kondo-insulator compound SmB_{6} are investigated as a function of crystal thickness and surface charge density, the latter tuned by ionic liquid gating with electrodes patterned in a Corbino disk geometry on a single (100) surface. By separately tuning bulk and surface conduction channels, we show conclusive evidence for a model with an insulating bulk and metallic surface states, with a crossover temperature that depends solely on the relative contributions of each conduction channel. The surface conductance, on the order of 100  e^{2}/h, exhibits a field-effect mobility of 133  cm^{2}/Vs and a large carrier density of ∼2×10^{14}  cm^{-2}, in good agreement with recent photoemission results. With the ability to gate modulate surface conduction by more than 25%, this approach provides promise for both fundamental and applied studies of gate-tuned devices structured on bulk crystal samples.

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