Magnetic properties of Tb4+/Tb3+ mixed valence oxide Ba1−xLaxTbO3 (x = 0 − 0.2)

We investigated the magnetic properties of Ba1−xLaxTbO3 with x ​= ​0, 0.1, and 0.2. The parent compound BaTbO3, which has single valent Tb4+ ions, undergoes an antiferromagnetic transition at the Néel temperature TN ​= ​33 ​K. Substitution of Ba2+ with La3+ reduces Tb4+ into Tb3+ and significantly enhances the magnetization (M) below around 25 ​K. The enhancement of the M can be explained by the formation of ferrimagnetic (FIM) or ferromagnetic (FM) clusters caused by a magnetic interaction between Tb4+ and Tb3+. At x ​= ​0.2, the TN merges into the onset temperature of the formation of the FIM or FM clusters.