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

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.