Local-moment formation and metal-nonmetal transition in Ca1−x Y x VO3 and Ca1−x Y x TiO3

Electron-doped metallic states of Ca1−x Y x VO3 and Ca1−x Y x TiO3 change into non-metallic states around x∼0.4 and 0.6, respectively. The residual resistivity in the metallic states increases with increasing effective magnetic moment or coefficient of T 2 term of resistivity. The effective moment reaches ∼ 0.5 µB/molecule in Ca1−x Y x VO3 and also in Ca1−x Y x TiO3 near the metal-nonmetal phase boundary. In these metallic states. ∼ 10% of 3d atoms seem to have large localized magnetic moments. In electron-doped metallic sample of Ca1−x Y x VO3, the temperature dependence of resistance shows no resistance-minimum. However, weak negative magneto-resistance is observed for the sample with x=0.2 up to 50 Tesla at 4.2 K.