Low temperature resistivity studies of SmB6: Observation of twodimensional variable-range hopping conductivity

TL;DR

This study investigates the low-temperature electrical resistance of SmB6, revealing that conduction below 3 K is dominated by two-dimensional variable-range hopping, especially near the surface, challenging the notion of resistance saturation.

Contribution

It demonstrates that the low-temperature conduction in SmB6 is governed by two-dimensional variable-range hopping rather than saturation, highlighting the importance of surface transport mechanisms.

Findings

No true resistance saturation below 3 K down to 70 mK.

Electrical conduction fits a 2D variable-range hopping model.

Hopping conduction is significant in the near-surface region.

Abstract

We studied electrical resistance of a single-crystalline SmB6 sample with a focus on the region of the "low-temperature resistivity plateau". Our observations did not show any true saturation of the electrical resistance at temperatures below 3 K down to 70 mK. According to our findings, temperature dependence of the electrical conduction in a certain temperature interval above 70 mK can be decomposed into a temperature-independent term and a temperature-activated term that can be described by variable-range hopping formula for two-dimensional systems, exp[-T0/T)^1/3]. Thus, our results indicate importance of hopping type of electrical transport in the near-surface region of SmB6.