Ab-Initio Study of Structural, Electronic, and Magnetic Properties of Magnetic Impurities in Rutile TiO2.

L. A. ERRICO, M. WEISSMANN, AND M. RENTERÍA

Lab. Tandar, CNEA, Bs. As

Workshop; International Workshop "At the Frontiers of Condensed Matter II: Magnetism, Magnetic Materials and Their Applications"; 2004

Lab. Tandar, CNEA

Integrating spin functionality into otherwise nonmagnetic materials has become a highly desirable goal in the last years. In particular, dilute magnetic impurities in semiconductors and oxides produce novel materials appealing for spintronics and optoelectronics (see, e.g., refs. [1-2] and other references therein). Magnetic dopants in nonmagnetic solids are assumed to couple with the electronic states of the host, but remaining magnetically active. While most of the dilute magnetic semiconductors have Curie temperatures much lower than room temperature, this is not so for Co-doped rutile and anatase TiO2 and rutile SnO2 [2], [3]. However, many questions remain regarding the precise location of Co in the host lattice and the underlying microscopic mechanism of long-range magnetic order.In this contribution we present a set of density-functional-theory-based calculations in the systems RxTi1-xO2 (R = Mn, Fe, Co, Ni). The calculations were performed with the WIEN97 implementation [4] of the full-potential linearized-augmented-plane-wave (FP-LAPW) method, assuming that the magnetic impurities substitutionally replace the Ti ions. The calculations were performed considering different dilutions and distributions of the impurities. The effects of the structural relaxations induced by the impurities in the host-lattice on the magnetic properties and the tendencies to ferromagnetism or antiferromagnetism are discussed and compared with previous calculations and experiments. Finally, from the study of different distributions of the impurities in the host, we calculate the exchange interaction parameters (J).