Increased room temperature ferromagnetism in Co-doped tetrahedral perovskite niobates.

Dilute magnetic semiconductors (DMSs), such as (In, Mn)As and (Ga, Mn)As prototypes, are limited to III-V semiconductors with Curie temperatures ( ) far from room temperature, thereby hindering their wide application. Here, one kind of DMS based on perovskite niobates is reported. BaM NbO ( = Fe, Co) powders are prepared by the composite-hydroxide-mediated method. The addition of elements endows BaM NbO with local ferromagnetism. The tetragonal BaCo NbO nanocrystals can be obtained by Co doping, which shows strong saturation magnetization ( ) of 2.22 emu g, a remnant magnetization ( ) of 0.084 emu g and a small coercive field ( ) of 167.02 Oe at room temperature. The calculations indicate that Co doping could lead to a 64% local spin polarization at the Fermi level ( ) with net spin DOS of 0.89 electrons eV, this result shows the possibility of maintaining strong ferromagnetism at room temperature. In addition, the trade-off effect between the defect band absorption and ferromagnetic properties of BaM NbO is verified experimentally and theoretically.