Molecular dynamics approach to magnetic alloys showing multi-step magnetic transitions: Fe20Cr80-xMnx alloys

A molecular dynamics (MD) approach which determines automatically the complex magnetic structures in itinerant electron systems is applied to Fe20Cr80-xMnx(0=<x=<40) alloys with use of 432 atoms in an MD unit cell. The results at 25K show the coexistence of the antiferromagnetic (AF) order on Cr sites and the spin glass (SG) order on Fe sites, with a small net magnetization. The SG is formed by the Fe ferromagnetic clusters each of which points upward or downward along the AF axis of Cr. The Mn magnetic moments are shown to enhance the AF arrangement as well as the amplitudes of Mn and Cr magnetic moments with increasing Mn concentration. The results are consistent with experimental data