Abstract
While correlated electron behavior is to be expected at oxide interfaces (IFs) involving Mott insulators, we show how strong correlations in the oxygen states may be necessary to account for observed insulating behavior at charged (001)-IFs between the band insulators and . Using correlated band theory applied to the O states, an insulating -type IF is obtained only when a disproportionated, charge-, orbital-, and spin-ordered O magnetic hole is formed, centered between ions in the layer at the IF. As an alternative explanation, charge compensation by oxygen vacancies that accommodate the holes as charge-conjugate F centers is modeled. For the -type IF, a charge disproportionated layer is obtained with ferromagnetic alignment of the spins resulting from occupied orbitals at checkerboard arranged sites. Electron hopping on a 50% occupied Ti sublattice (a quarter-filled band) and/or lattice relaxations are discussed as origin of the measured conductivity.
4 More- Received 3 February 2006
DOI:https://doi.org/10.1103/PhysRevB.74.035112
©2006 American Physical Society