nanowire*

SmB₆, as a topological Kondo insulator, has spin-momentum-locked surface states and fully insulating bulk, which presents promising spintronic applications. Here, we report on the magnetotransport properties of individual SmB₆ nanowires. With decreasing temperature below 10 K, the surface states dominate the transport behavior as reflected by the resistance saturation. At 1.5 K, a transition from negative to positive magnetoresistance occurs with gradually increasing the bias current. The nonlocal measurements indicate that the surface state transport is spin polarized, and the spin diffusion length is as long as 0.5 μm. Bias current-modulated two-channel transport is employed to explain the observed sign reversal of the magnetoresistance.