Effect of Fe substitution with Co on the magnetic properties of Fe80P13C7 amorphous alloys: An abinitio molecular dynamics study

In this study, we analyze the effect of Fe substitution with Co on the magnetic properties of Fe ₈₀P ₁₃C ₇ amorphous alloy using experimental measurements and first-principle molecular dynamic calculations of the distribution functions, Voronoi polyhedra, and density of states of Fe _80-xCo _xP ₁₃C ₇ (x = 0, 5, 10, 15 at.%) alloys. The experimental results demonstrate that the saturation magnetization ( M_s) of Fe _80-xCo _xP ₁₃C ₇ (x = 0, 5, 10, 15 at.%) increases and then decreases with increasing Co content, and that maximum M_s is achieved when the composition of Co is 5 at.%. This trend is consistent with the one determined using simulations. Compared to the other amorphous alloys investigated herein, Fe ₇₅Co ₅P ₁₃C ₇ exhibits the highest local symmetry, which explains why it has the largest exchange splitting energy and largest M_s. In addition, increasing substitution of Fe atoms with Co does not appreciably affect the magnetic moment of Co atoms, but it increases the magnetic moment of Fe atoms, particularly those adjacent to Co. This indicates that Co atoms can induce an increase in the magnetic moment of the Fe atoms surrounding them.