Order-disorder induced magnetic structures of FeMnP0.75Si 0.25

Abstract

We report on the synthesis and structural characterization of the magnetocaloric FeMnP0.75Si0.25 compound. Two types of samples (quenched and slowly cooled) were synthesized and characterized structurally and magnetically. We have found that minor changes in the degree of crystallographic order causes large changes in the magnetic properties. The slow-cooled sample, with a higher degree of order, is antiferromagnetic. The quenched sample has a net moment of 1.26 μB per formula unit and ferrimagnetic behavior. Theoretical calculations give rather large values for the Fe and Mn magnetic moments, both when occupied on the tetrahedral and the pyramidal lattice sites. © 2011 American Physical society.