Weak Antilocalization and Linear Magnetoresistance in The Surface State of SmB6

TL;DR

This paper reports on the metallic surface state of SmB6 showing weak-antilocalization and linear magnetoresistance, indicating topological surface conduction and Kondo effects at very low temperatures.

Contribution

It provides transport measurement evidence of spin-momentum locking and Kondo-related behaviors in SmB6's surface state, supporting its classification as a topological Kondo insulator.

Findings

Surface state conduction persists down to mK temperatures.

Observation of weak-antilocalization consistent with spin-momentum locking.

Unusual linear magnetoresistance similar to other topological materials.

Abstract

Strongly correlated Kondo insulator SmB6 is known for its peculiar low temperature residual conduction, which has recently been demonstrated to arise from a robust metallic surface state, as predicted by the theory of topological Kondo insulator (TKI). Photoemission, quantum oscillation and magnetic doping experiments have provided evidence for the Dirac-like dispersion and topological protection. Questions arise as whether signatures of spin-momentum locking and electron interaction could be resolved in transport measurements. Here we report metallic conduction of surface state down to mK temperatures with saturation behaviors suggestive of Kondo effect. We observe in the surface state the weak-antilocalization (WAL) effect that is in agreement with a spin-momentum locked metallic surface. At larger perpendicular magnetic fields, the surface state exhibits an unusual linear magnetoresistance similar to those found in Bi-based topological insulators and in graphene. (Correspondence to: xia.jing@uci.edu)