Synthesis, Structural, and Magnetic Characterization of a New Ferrimagnetic Oxide:  YFeMnO5

A new ferrimagnetic oxide of stoichiometry YFeMnO5 has been prepared in polycrystalline form by wet-chemistry procedures followed by thermal treatments under high oxygen pressure conditions. This material has been characterized by X-ray and neutron powder diffraction (NPD), magnetotransport, specific heat, and magnetization measurements. YFeMnO5 is isostructural with RMn2O5 oxides; its crystal structure has been Rietveld refined from NPD data in the space group Pbam, and it contains infinite chains of Mn4+O6 octahedra sharing edges, linked together by Fe3+O5 pyramids and YO8 units. A certain level of disorder has been found between both metallic positions; about 5% of Mn cations is replaced by Fe and vice versa. The magnetic measurements and the analysis of the temperature-dependent NPD patterns show that YFeMnO5 orders below T c ≈ 165 K with a ferrimagnetic structure characterized by the propagation vector k = 0. The spin arrangements for the Mn4+ ions (4f site) and Fe3+ ions (4h site) are given by the basis vectors (0,0,F z ) and (0,0,F z ‘), respectively. The Mn and Fe ordered magnetic moments are oriented along the c axis; at T = 2.9 K the magnitudes of the magnetic moments are 2.30(3) and −3.89(6) μB, respectively.