Ferromagnetism in LaCoO$_3$. Relationship between crystal structure, morphology and magnetic properties

Abstract

It is known that in a weak magnetic field ($H < 1$~kOe) at $T < T_C \approx 87$~K, rare-earth cobalt oxide LaCoO$_3$ has ferromagnetic properties. The physical mechanism of the ferromagnetism emergence in LaCoO$_3$ is still remains unclear. We provided experimental evidence of the ferromagnetism and crystal lattice interconnection -- the cause of ferromagnetic ordering is the near surface (defects) structural stresses. A theoretical model is proposed, within the framework of which the mechanism of the emergence of the magnetically ordered state in LaCoO$_3$ is discussed.