Composition dependence of magnetic properties in perpendicularly magnetized epitaxial thin films of Mn-Ga alloys

Abstract

Mn-Ga binary alloys show strong magnetism and large uniaxial magnetic anisotropy even though these alloys do not contain any noble, rare-earth metals or magnetic elements. We investigate the composition dependence of saturation magnetization ${M}_{\mathrm{S}}$ and uniaxial magnetic anisotropy ${K}_{\mathrm{u}}$ in epitaxial films of Mn${}_{x}$Ga${}_{1\ensuremath{-}x}$ alloys ($x\ensuremath{\sim}0.5$--0.75) grown by magnetron sputtering. The ${M}_{\mathrm{S}}$ values decrease linearly from approximately 600 to 200 emu/cm${}^{3}$ with increasing $x$, whereas the ${K}_{\mathrm{u}}$ values decrease slightly from approximately 15 to 10 Merg/cm${}^{3}$ with increasing $x$. These trends are distinct from those for known tetragonal hard magnets obtained in a limited composition range in Mn-Al and Fe-Pt binary alloys. These data are analyzed using a localized magnetic moment model.