Room temperature short-range ferromagnetic order in Ni-doped tetragonal perovskite niobate

Abstract

Here, we report a strong room-temperature magnetism in Ni-doped BaNbO3. The tetragonal BaNixNb(1-x)O3-δ nano-powders are prepared by the composite-hydroxide-mediated method. The as-prepared BaNixNb(1-x)O3-δ has a saturation magnetization (Msat) of 2.54 emu/g, a remnant magnetization (Mr) of 0.228 emu/g, and a small coercive field (Hc) of 99.14 Oe at room temperature, presenting as a short-range magnetic order. The Ni-doping leads to an incommensurate valence state of Nb, and the oxidation state of Ni in the matrix is + 2. It brings not only strong local spin polarization to the matrix, but also balances the oxygen defects and gives rise to a more doping content. The strong magnetism originated from the existence of short-range magnetic order and the strong local net spin polarization at the Fermi level (EF), which are proved by the first-principle calculations.