Causes of the Metamagnetism in a Disordered EuMn0.5Co0.5O3 Perovskite

The magnetic properties of the EuMn 0.5 Co 0.5 O 3 perovskite synthesized under various conditions are studied in fields up to 140 kOe. The sample synthesized at T = 1500°C is shown to exhibit a metamagnetic phase transition, which is irreversible below T = 40 K, and the sample synthesized at T = 1200°C demonstrates the field dependence of magnetization that is typical of a ferromagnet. Both samples have T 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 2+ and Mn 4+ ions leads to ferromagnetism. The noncollinear phase is formed due to the competition between positive Co 2+ –Mn 4+ and negative Mn 4+ –Mn 4+ and Co 2+ –Co 2+ interactions, which make almost the same contributions, and to the existence of a high magnetic anisotropy.