Manganese-vacancy complexes induced room temperature ferromagnetism in Mn/Mg co-doped In2O3 diluted magnetic semiconductors

Abstract

Abstract The (In0.98-xMnxMg0.02)2O3 (x = 0, 0.02, 0.05, 0.07, 0.11) films were deposited on Si (001) and ultra-white glass substrates using the RF-magnetron sputtering technique. The effects of Mn doping on the structural, optical, magnetic and transport properties of films were systematically investigated. The XANES and EXAFS spectra at Mn K-edge as well as the corresponding multiple-scattering calculations of XANES spectra clearly indicate that the doped Mn ions replace In ions in the In2O3 matrix with +2 oxidation states and form Mn2+-VO complexs in the nearest coordination shell of Mn. The decreased film transmittance and red shift of the optical band gap are observed with increasing Mn concentration, which can be ascribed to sp-d exchange interaction associated with the Mn dopants. All the films exhibit intrinsic room-temperature ferromagnetic ordering and the semiconducting behavior with the transport mechanism of Mott variable range hopping (VRH). The ferromagnetic properties of the films can consider being due to the Mn2+-vacancy complexes induced magnetic interaction by the overlapping of bound magnetic polarons.