Magnetic-field-induced Anderson localization in orbital selective antiferromagnet BaMn$_2$Bi$_2$

Abstract

We report a metal-insulator transition (MIT) in the half-filled mutltiorbital antiferromagnet (AF) BaMn2Bi2 that is tunable by perpendicular magnetic field. Instead of an Anderson-Mott mechanism usually expected in strongly correlated systems, we find by scaling analyses that the MIT is driven by an Anderson localization. Electrical and thermoelectrical transport measurements in combination with electronic band calculations reveal a strong orbital-dependent correlation effect, where both weakly and strongly correlated 3d-derived bands coexist with decoupled charge excitations. Weakly correlated holelike carriers in the dxy-derived band dominate the transport properties and exhibit the Anderson localization, whereas other 3d bands show clear Mott-like behaviors with their spins order into AF sublattices. The tuning role played by the perpendicular magnetic field supports a strong spin-spin coupling between itinerant holelike carriers and the AF fluctuations, which is in sharp contrast to the weak charge coupling.