Theoretical study of the complex antiferromagnetic Heusler alloys Pd[formula omitted]MnAl, Pd[formula omitted]MnIn, and Pt[formula omitted]MnAl

Abstract

The complex antiferromagnetic (AFM) phases displayed by the Heuser alloys Pd2MnAl, Pd2MnIn, and Pt2MnAl, are theoretically studied. The crystalline structure, electronic, and magnetic properties are calculated within the ab initio density functional theory. The super unit cell considered to describe the various magnetic arrangements contains 128 atoms. We analyzed the ferromagnetic (FM) and the three different antiferromagnetic (AFM) phases and found that the Pd2MnAl crystalline structure is orthorhombic with dimensions 6.055, 6.461, 6.026 Å. The AFM state with the lowest energy is the AFM3 with a Mn magnetic moment of 3.813 μB. The Pd2MnIn crystallizes in an orthorhombic structure with lattice parameters 6.249, 6.763, 6.227 Å. The ground state antiferromagnetic arrangement is also of type 3 with a Mn magnetic moment of 3.932 μB. The Pt alloy crystallizes in an orthorhombic structure with lattice dimensions of 6.029, 6.906, and 5.683 Å. In this case, the antiferromagnetic ground state is of type 1 with a Mn magnetic moment of 3.716 μB. The Pd and Pt d states are deep in energy and do not interact much with the Mn d states. This produces, in Pd and Pt, no magnetic polarization.