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

Magnetic susceptibility chi(T) (2 less than or equal to T less than or equal to 400 K), electrical resistivity rho(T) (2 less than or equal to T less than or equal to 300 K), and Hall effect of the distorted perovskite CaRu1-xRhxO3 with 0 less than or equal to x less than or equal to 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. (C) 1997 American Institute of Physics.