Transport gap in SmB6protected against disorder

Abstract

The inverted resistance method was used in this study to extend the bulk resistivity ofSmB6to a regime where the surface conduction overwhelms the bulk. Remarkably, regardless of the large off-stoichiometric growth conditions (inducing disorder by samarium vacancies, boron interstitials, etc.), the bulk resistivity shows an intrinsic thermally activated behavior that changes ∼7–10 orders of magnitude, suggesting thatSmB6is an ideal insulator that is immune to disorder.