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

A polycrystalline sample with SrFe0.5Co0.5O3-δ stoichiometry has been prepared under moderate pressures of 2GPa 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 295K, 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 TC∼330K, 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)μB at T=2 and 295K, respectively. Transport measurements show a semiconducting behaviour, and a negative magnetoresistance (MR) of -6.5% is observed at T=5K for H=9T