On the magnetic structure of (Fe1−xMnxFe1−xMnx)Pt: A first-principles study

•The stabilities of the magnetic structures are highly composition-dependent.•The flipping of Mn moments exists only in dilute alloys.•The competition between ferromagnetic and antiferromagnetic couplings dominates the stability of magnetic structures.

This study investigates the composition dependence of magnetic structures of (Fe1−xMnxFe1−xMnx)Pt using first-principles method. A series of possible magnetic configurations are considered in the calculation to compare the relative stabilities after structural optimization, based on which, together with the comparison between theoretical and experimental magnetic properties, the results largely support the experimental finding in powders. The experimentally found stability of ferrimagnetic state in films with a wide composition range of x≤0.5x≤0.5 is not fully supported by this study. The composition-dependent magnetic structures are discussed according to the exchange interactions.