Multiple channel transport properties of topological surface states in SmB6 nanoribbons

SmB6, a topological Kondo insulator, possesses topologically protected surface states, in which carrier mobility is supposed to be high but is significantly varied in orders of magnitude dependent upon characterization methods. Herein, we performed magnetoresistance measurements on a Hall-bar device constructed on a highly uniform SmB6 nanoribbon with (001) surface grown by chemical vapor deposition. Unusual non-linear Hall resistance was observed at low temperature and explained with a two-carrier model. The two types of carriers were attributed to two types of Fermi pockets on the Brillouin zone of the SmB6 (001) surface. The Fermi pocket on Γ point provided high hole mobility up to 1.4×103 cm2/V s but low hole density at a temperature of 2.2 K. On the other hand, the Fermi pockets on X points supplied low electron mobility down to 1.8 cm2/V s but high electron density. The identification of the two types of pockets laid the foundation for the understanding of the transport via the topological surface states of the SmB6 (001) surface.