Surface ferromagnetism of LaCoO3 crystals

Abstract Linear and nonlinear magnetic susceptibilities of a LaCoO 3 particle sample were measured to shed light on the surface ferromagnetism of LaCoO 3 . The ferromagnetic transition temperature T C estimated from the nonlinear magnetic susceptibility agrees well with that inferred from Kouvel–Fisher's analysis of the linear susceptibility, while the critical exponent γ deduced simultaneously from the same analysis is incompatible with any values reported for 2 d and 3 d ferromagnetism. The results are discussed in view of surface and/or size effects in detail.