First-principles study of the magnetism in indium oxide-based dilute magnetic semiconductors

Abstract

Using In2O3 as a host matrix, extensive density functional theory (DFT) calculations have been performed to study the mechanism of ferromagnetism in In2O3-based system. As a conventional approach to introduce local magnetic moment by transition metal doping, Fe-doped In2O3 (IFO) is the suitable prototype due to its high solubility of Fe in In2O3. Our DFT studies show that the ground state of pure IFO is antiferromagnetic. The coexistence of O vacancy (VO) and Cu co-doping (IFCO-VO) can greatly enhance the stability of the ferromagnetism. The role of Cu ions is to act as super-exchange mediators causing an indirect ferromagnetic (FM) coupling between Fe ions. In favor of the FM state, Cu ions prefer to locate adjacent to the Fe ions to facilitate Fe1-O1-Cu-O2-Fe2 coupling chains. Alternative approaches to introduce local magnetic moment are 2p elements or alkali metal doping. Our calculations show that, in case of the 2p element N doping, the FM coupling between N dopants is activated through holes induced by N doping via a N1:p-Inbr:d/p-N2:p coupling chain in short N-N separations. The FM coupling in alkali cation doped In2O3 is activated by intra- and inter-correlation of the XIn-6ONN complexes (X = alkali metal).