Disappearance of the itinerant electronic ferromagnetism in layered compound Sr₂VO₃CoAs due to self-electron-doping effect

We successfully synthesized a polycrystalline sample of Sr₂VO₃CoAs, a new member of the group of compounds with CoAs layers. Physical property measurement results show that the magnetic moments of Co do not show itinerant electronic ferromagnetism, unlike other compounds with CoAs layers, whereas the magnetic moments of V show antiferromagnetic ordering below 140 K separately from the magnetic moments of Co. By partially substituting Fe for Co in Sr₂VO₃CoAs, we successfully induced the itinerant electronic ferromagnetism of magnetic moments of Co with T_C ∼ 50 K. These results show that the electronic state of CoAs layers of Sr₂VO₃CoAs is naturally in an "overdoped" state, although that of other members with CoAs layers is in the optimally doped state for the itinerant electronic ferromagnetism. Sr₂VO₃CoAs is overdoped because of the self-electron doping from V to the 3d band of Co, as observed in the Fe analogue. (author)