Itinerant-to-localized electron transition in perovskite CaRu1−xRhxO3

Abstract

Magnetic susceptibility χ(T) (2⩽T⩽400 K), electrical resistivity ρ(T) (2⩽T⩽300 K), and Hall effect of the distorted perovskite CaRu1−xRhxO3 with 0⩽x⩽0.35 were measured. This study indicates that the magnetic and transport properties of CaRuO3, a paramagnetic conductor with a narrow 4d-band, depend in an extremely sensitive way on the degree of band filling and bandwidth. Slight Rh doping, while retaining the crystals structure, effectively narrows the 4d-band, and enhances the spin correlation. The occurrence of the enhanced spin correlation is accompanied by an itinerant-to-localized electron transition and a change in crystallographic constants. The results presented together with others strongly suggests that CaRuO3, is on the verge of the metal-insulator transition and magnetic ordering.