Weak antilocalization and linear magnetoresistance in the surface state of SmB6

The 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, 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 to whether signatures of spin-momentum locking and electron interaction could be resolved in transport measurements. Here we report metallic conduction of surface down to mK temperatures. We observe in the surface the weak-antilocalization (WAL) effect at small perpendicular magnetic fields. At larger perpendicular magnetic fields, the surface exhibits an unusual linear magnetoresistance similar to those found in Bi-based topological insulators and in graphene.