High pressure synthesis, crystal, magnetic structure and magnetotransport of SrFe0.5Co0.5O3-delta

摘要

A polycrystalline sample with SrFe0.5Co0.5O3-delta stoichiometry has been prepared under moderate pressures of 2 GPa in the presence of KClO4 as oxidizing agent. The crystallographic and magnetic structures have been studied from neutron powder diffraction (NPD), complemented with magnetotransport and magnetic susceptibility data. The study of the crystallographic structure confirms that this compound, with the actual stoichiometry SrFe0.5Co0.5O2.88(3), is a simple cubic perovskite at 2 and 295 K, defined in the Pm-3m space group, where Fe and Co atoms are distributed at random over the B positions. The magnetic measurements show that SrFe0.5Co0.5O2.88 is a ferromagnet with T-C approximate to 330 K, which is also confirmed by neutron diffraction: the magnetic structure is collinear, characterized by a propagation vector k = 0; the ordered magnetic moment values for the (Fe4+,Co4+) cations are 1.54(9) and 0.65(15)(mu B) at T = 2 and 295 K, respectively. Transport measurements show a semiconducting behaviour, and a negative magneto resistance (MR) of -6.5% is observed at T = 5 K for H = 9 T. (c) 2006 Elsevier Inc. All rights reserved.