Dilute magnetic semiconductors (DMSs), such as (In, Mn)As and (Ga, Mn)As prototypes, are limited to III–V semiconductors with Curie temperatures (T_c) far from room temperature, thereby hindering their wide application. Here, one kind of DMS based on perovskite niobates is reported. BaM_xNb_(1-x)O_3-δ (M=Fe, Co) powders are prepared by the composite-hydroxide-mediated method. The addition of M elements endows BaM_xNb_(1-x)O_3-δ with local ferromagnetism. The tetragonal BaCo_xNb_(1-x)O_3-δ nanocrystals can be obtained by Co doping, which shows strong saturation magnetization(M_sat) of 2.22 emu/g, a remnant magnetization(M_r) of 0.084 emu/g, and a small coercive field(H_c) of 167.02 Oe at room temperature. The ab initio calculations indicate that Co doping could lead to a 64% local spin polarization at the Fermi level(E_F) with net spin DOS of 0.89 electrons·eV^-1, 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_xNb_(1-x)O_3-δ is verified experimentally and theoretically.

The DFT data was collected from the ab initio calculation results of BaM_xNb_(1-x)O_3-δ, which is performed by CASTEP. M(H) data was collected by the field-dependent magnetization measurement. XRD data was collected by X-ray diffraction. XPS data was collected by X-ray photoelectron spectroscopy. UV data was collected by UV-vis absorption measurement.

M(H), XRD, XPS, and UV data are all raw data given by the instruments and have not been processed.