Kondo insulator SmB6 under strain: surface dominated conduction near   room temperature
  SmB6 is a strongly correlated mixed-valence Kondo insulator with a newly discovered surface state, proposed to be of non-trivial topological origin. However, the surface state dominates electrical conduction only below T* ~ 4 K limiting its scientific investigation and device application. Here, we report the enhancement of T * in SmB6 under the application of tensile strain. With 0.7% tensile strain we report surface dominated conduction at up to a temperature of 240 K, persisting even after the strain has been removed. This can be explained in the framework of strain-tuned temporal and spatial fluctuations of f-electron configurations, which might be generally applied to other mixed-valence materials. We note that this amount of strain can be indued in epitaxial SmB6 films via substrate in potential device applications. 
A. Stern, M. Dzero, V. M. Galitski, Z. Fisk, and J. Xia
cond-mat.str-el cond-mat.mes-hall cond-mat.mtrl-sci