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 (Tc) far from room temperature, thereby hindering their wide application. Here, one kind of DMS based on perovskite niobates is reported. BaMxNb(1-x)O3-δ (M=Fe, Co) powders are prepared by the composite-hydroxide-mediated method. The addition of M elements endows BaMxNb(1-x)O3-δ with local ferromagnetism. The tetragonal BaCoxNb(1-x)O3-δ nanocrystals can be obtained by Co doping, which shows strong saturation magnetization(Msat) of 2.22 emu/g, a remnant magnetization(Mr) of 0.084 emu/g, and a small coercive field(Hc) 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(EF) 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 de...

稀磁半导体（dilute magnetic semiconductors，DMSs），例如经典的锰掺杂砷化铟[(In,Mn)As]与锰掺杂砷化镓[(Ga,Mn)As]，其应用仅局限于Ⅲ-Ⅴ族半导体，且居里温度（Curie temperature，Tc）远低于室温，极大阻碍了其大规模推广应用。本文报道了一种基于钙钛矿铌酸盐的稀磁半导体材料。研究通过复合氢氧化物法（composite-hydroxide-mediated method）制备了BaMₓNb_(1-x)O_(3-δ)（M=Fe、Co）粉体。掺杂过渡金属元素M可赋予BaMₓNb_(1-x)O_(3-δ)局域铁磁性。通过钴掺杂可获得四方相的BaCoₓNb_(1-x)O_(3-δ)纳米晶体，该材料在室温下展现出优异的磁性能：饱和磁化强度（saturation magnetization，Msat）达2.22 emu/g，剩余磁化强度（remnant magnetization，Mr）为0.084 emu/g，矫顽场（coercive field，Hc）仅为167.02 Oe。从头算（ab initio calculations）结果表明，钴掺杂可在费米能级（Fermi level，EF）处实现64%的局域自旋极化，净自旋态密度为0.89 electrons·eV⁻¹，该结果证明了该材料在室温下维持强铁磁性的可行性。此外，在……之间存在权衡效应。