We have studied the effect of cobalt substitution in $L1_{ 0}$-Fe$_{ 1-x}$Co$_{ x}$Pt films by means of x-ray magnetic circular dichroism (XMCD) and first-principles calculations. The magnetic moments of Fe ($\sim$2.5 $\mu_{ \rm B}$) and Co ($\sim$1.5 $\mu_{ \rm B}$) deduced using XMCD were almost unchanged upon Co doping, and the net magnetization decreases with increasing Co content. Calculation also showed that the 3$d$ electrons that have been added by Co substitution occupy only spin-down bands.
Categories: cond-mat.mtrl-sci