Dependence of band gaps in d-electron perovskite oxides on magnetism

Understanding the controlling principles of band gaps trends in d electron\nperovskites is needed both for gauging metal-insulator transitions, as well as\ntheir application in catalysis and doping. The magnitude of this band gap is\nrather different for different magnetic spin configurations. We find via\nelectronic structure theory that the factors that connect gapping magnitudes to\nmagnetism depend on the nature of the band edge orbital character (BEOC) and\nsurprisingly scale with the number of antiferromagnetic contacts z$_i$ between\nneighboring transition metal ions. The dependence is weak when the BEOC are\n(d,d)-like ("Mott insulators"), whereas this dependence is rather strong in\n(p,d)-like ("charge transfer" insulators). These unexpected rules are traced to\nthe reduced orbital interactions through the increase in the number of\nantiferromagnetic contacts between transition metal ions. The impact of\nmagnetic order is not limited to the band gap magnitude and includes also the\nmagnitude of lattice distortions connected to the electronic structure. These\nresults highlight the importance of establishing in electronic structure theory\nof gap-related phenomena (doping, transport, metal-insulator transitions,\nconductive interfaces) the appropriate magnetic order.\n