Effect(s) of Cobalt Substitution in $L1_{0}$-(Fe,Co)Pt Thin Films

TL;DR

This study investigates how cobalt substitution affects the magnetic properties of $L1_{0}$-Fe$_{1-x}$Co$_{x}$Pt thin films using experimental XMCD techniques and first-principles calculations, revealing unchanged local moments but decreasing net magnetization.

Contribution

It combines experimental and computational methods to analyze the electronic and magnetic effects of cobalt doping in FePt thin films, providing new insights into their magnetic behavior.

Findings

Fe and Co magnetic moments remain nearly unchanged with Co doping

Net magnetization decreases as Co content increases

Added 3d electrons occupy only spin-down bands

Abstract

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.