Magnetic field induced Anderson localization in the orbital-selective antiferromagnet BaMn2Bi2

We report a metal-insulator transition (MIT) in the half-filled multiorbital antiferromagnet (AFM) BaMn2Bi2 that is tunable by a magnetic field perpendicular to the AFM sublattices. 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 dxyderived band dominate the transport properties and exhibit the Anderson localization, whereas other 3d bands show clear Mott-like behaviors with their spins ordered into AFM sublattices. The tuning role played by the perpendicular magnetic field supports a strong spin-spin coupling between itinerant holelike carriers and the AFM fluctuations, which is in sharp contrast to their weak charge coupling.

Automated summary

We report a metal-insulator transition (MIT) in the half-filled multiorbital antiferromagnet BaMn2Bi2 that is tunable by a magnetic field. Scaling analyses reveal that the MIT is driven by Anderson localization instead of the expected Anderson-Mott mechanism. Electrical and thermoelectrical transport measurements, combined with electronic band calculations, show strong orbital-dependent correlation effects.