Abstract
While evidence of a topologically nontrivial surface state has been identified in surface-sensitive measurements of , a significant experimental concern is that no signatures have been observed in bulk transport. In a search for such states, nominally undoped single crystals of with carrier densities approaching and very high mobilities exceeding have been studied. A comprehensive analysis of Shubnikov-de Haas oscillations, Hall effect, and optical reflectivity indicates that the measured electrical transport can be attributed solely to bulk states, even at 50 mK at low Landau-level filling factor, and in the quantum limit. The absence of a significant surface contribution to bulk conduction demonstrates that even in very clean samples, the surface mobility is lower than that of the bulk, despite its topological protection.
- Received 12 May 2010
DOI:https://doi.org/10.1103/PhysRevB.81.241301
©2010 American Physical Society