Localized and itinerant electronic states at the insulator–metal transition in Y1−xCaxVO3+δ: evidence from electric transport, magnetic properties and XASspectroscopy

Abstract

Electron transport and macroscopic magnetic properties of the perovskite mixed-valent system Y_1−xCa_xVO_3+δ were investigated by means of resistivity and magnetic susceptibility measurements. As is shown by transport data, the system undergoes an insulator–metal transition on doping with Ca beyond the threshold concentration x ≈ 0.35. However, magnetic response data evidence a more complex scenario in which localized-electrons giving rise to magnetism coexist with itinerant electrons, well beyond the metal–insulator (M–I) transition. In the insulating compounds, susceptibility data suggest the occurrence of short-range order slightly above T ≈ 114 K, which is reminiscent of the temperature at which the parent compound YVO₃ undergoes a transition to an antiferromagnetic long-range order. In the metallic samples, evidence of a possible electronic phase segregation are found.