Topological Surface Conduction in YbB$_{12}$

Abstract

We investigate transport properties of single crystals and microstructures of prototype Kondo insulator YbB$_{12}$ to investigate the topological surface state (SS). We prepared the microstructures by employing focused ion beam method and controlled sample thickness down to several micrometers. In all samples, the temperature dependence of the electrical resistivity is insulating at high temperatures, and the resistivity exhibits a plateau at low temperatures. The magnitude of the plateau value decreases with reducing sample thickness, which is quantitatively consistent with the surface electronic conduction in the bulk insulating YbB$_{12}$. Moreover, the magnetoresistance of the microstructures exhibits a weak-antilocalization effect at low field. These results are consistent with the presence of topologically protected SS, suggesting that YbB$_{12}$ is a candidate material of the topological Kondo insulator (TKI). The high field resistivity measurements up to $\mu _0H=$ 50 T of the microstructures provide supporting evidence that the quantum oscillations (QOs) in the resistivity of YbB$_{12}$ occur in the insulating bulk.