Kondo insulator SmB6 under strain: surface dominated conduction near room temperature

TL;DR

Applying tensile strain to SmB6 significantly raises the temperature at which surface conduction dominates, from below 4 K to around 240 K, enabling room-temperature surface conduction in this topological Kondo insulator.

Contribution

This work demonstrates that tensile strain can enhance the surface conduction temperature in SmB6, opening pathways for room-temperature applications of topological Kondo insulators.

Findings

Surface dominated conduction observed up to 240 K under 0.7% tensile strain.

Strain-induced enhancement persists even after removing strain.

Strain can be applied via substrates in epitaxial films for device use.

Abstract

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.