Effect of the oxygen nonstoichiometry on the structure and magnetic properties of Nd₂CoMnO_6+<i>δ</i> double perovskites

Abstract

Abstract The properties of Nd 2 CoMnO 6+ δ ( δ up to 0.12) were investigated by means of neutron powder diffraction and magnetization measurements. It is found that the samples exhibit partial ordering of Co and Mn ions which strongly affects the magnetic properties. Ionic disorder increases with the oxygen content. According to neutron diffraction the stoichiometric and nonstoichiometric samples show ferromagnetic components which decreases as the oxygen content increases. The magnetization study of the strongly oxidized sample reveals a metamagnetic behavior. It is assumed that metamagnetism results from clusters with short‐range antiferromagnetic order. Enhancement of the oxygen content leads to a conversion of Co 2+ into low spin Co 3+ and the appearance of a cationic vacancy which destroys the ionic order and stabilizes the overall antiferromagnetic behavior. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)