Valence states and metamagnetic phase transition in partially B-site-disordered perovskite EuMn_0.5Co_0.5O₃

The valence states of transition metals were studied by measuring the x-ray absorption spectra at both Mn L-2,L-3 and Co L-2,L-3 edges of partially B-site-disordered perovskite EuMn0.5Co0.5O3. By comparison with analogous spectra in various Co- and Mn-based compounds, the divalent state of the Co ions and the tetravalent state of the Mn ions were established analogous toMn(4+)/Co2+ charge ordering found by Dass and Goodenough [Phys. Rev. B 67, 014401 (2003)] in LaMn0.5Co0.5O3. The specific heat and magnetic susceptibility data indicate the formation of the magnetically ordered state at T-C similar to 120 K. The first-order metamagnetic transitions seen in EuMn0.5Co0.5O3 at T < T-C suggest the existence of antiferromagnetic and/or paramagnetic clusters embedded into the ferromagnetic matrix