Causes of the Metamagnetism in a Disordered Eu[Mn.sub.0.5][Co.sub.0.5][O.sub.3] Perovskite

The magnetic properties of the Eu[Mn.sub.0.5][Co.sub.0.5][O.sub.3] perovskite synthesized under various conditions are studied in fields up to 140 kOe. The sample synthesized at T = 1500[degrees]C is shown to exhibit a metamagnetic phase transition, which is irreversible below T = 40 K, and the sample synthesized at T = 1200[degrees]C demonstrates the field dependence of magnetization that is typical of a ferromagnet. Both samples have [T.sub.C] = 123 K and approximately the same magnetization in high magnetic fields. The metamagnetism is assumed to be related to a transition from a noncollinear ferromagnetic phase to a collinear phase, and the presence of clusters with ordered [Co.sup.2+] and [Mn.sup.4+] ions leads to ferromagnetism. The noncollinear phase is formed due to the competition between positive [Co.sup.2+]-[Mn.sup.4+] and negative [Mn.sub.4+]- [Mn.sup.4+] and [Co.sup.2+]-[Co.sup.2+] interactions, which make almost the same contributions, and to the existence of a high magnetic anisotropy.