Influence of Mo-doping on the magnetic properties of V 2O 3

Abstract

The magnetic study of new Mo-doped vanadium sesquioxides (V 1− x Mo x ) 2− δ O 3 revealed two unexpected behaviours. On the one hand, the measured effective magnetic moment in the paramagnetic state at room temperature exhibits a peculiar variation against Mo-doping: first it increases for the lower doping rates ( x⩽5% with a metal/insulator transition), then decreases for purely metallic compositions ( x>5%). This could be explained by the existence of a spin–orbit coupling between cations. On the other hand, a very weak ferromagnetic component has been evidenced in addition to the mainly antiferromagnetic behaviour. This ferromagnetism is correlated to the partial oxidation of the samples in air at room temperature. The magnetic structure of Mo-doped compounds is similar to that of V 2O 3, but with a small rotation of the magnetic moment as a function of doping. In contrast with the effect of titanium doping, no magnetic ordering has been observed at low temperature for the highly Mo-doped samples ( x>5%), which remain metallic over the whole thermal range.