title: Atomic control of conductivity versus ferromagnetism in wide-gap oxides via selective doping: V, Nb, Ta in anatase TiO2.
abstract: We identify two general types of electronic behaviors for transition-metal impurities that introduce excess electrons in oxides. (i) The dopants introduce resonant states inside the host conduction band and produce free electrons; (ii) the dopants introduce a deep gap state that carries a magnetic moment. By combining electronic structure calculations, thermodynamic simulations, and percolation theory, we quantify these behaviors for the case of column V-B dopants in anatase TiO2. Showing behavior (i), Nb and Ta dopants can convert the insulator TiO2 into a transparent conductor. Showing behavior (ii), V dopants could convert nonmagnetic TiO2 into a ferromagnet. Whether a dopant shows behavior (i) or (ii) is encoded in its atomic d orbital energy.
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401, USA.
authors.forename: Jorge
authors.initials: J
authors.lastname: Osorio-Guillén
authors.forename: Stephan
authors.initials: S
authors.lastname: Lany
authors.forename: Alex
authors.initials: A
authors.lastname: Zunger