Magnetic Properties of Single Crystal Fe$_{1-x}$Ga$_{x}$ Thin Films

Single crystal thin films of the highly magnetostrictive Fe$_{1-x}$Ga$_{x}$ alloy have been prepared on GaAs(001), with a ZnSe buffer layer, and MgO(001) substrates by molecular beam epitaxy (MBE). The saturation magnetization of the samples, as determined by vibrating sample magnetometry (VSM) and Rutherford backscattering (RBS), shows a reduction as a function of Ga concentration which closely follows a simple dilution model up to a concentration of 25{\%} Ga where the magnetization falls more abruptly than simple dilution allows. X-ray magnetic circular dichroism (XMCD) performed at the Fe and Ga L$_{2,3}$-edges, along with \textit{ab-initio} density functional (GGA) calculations, ascribe this trend to a decrease in the elemental Fe moment and an induced moment in the gallium of 0.1 $\mu _{B}$ anti-aligned to the Fe, establishing Fe$_{1-x}$Ga$_{x}$ as a ferrimagnetic system.