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

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 MS and uniaxial magnetic anisotropy Kᵤ in epitaxial films of MnₓGa_1-x alloys (x~0.5--0.75) grown by magnetron sputtering. The MS values decrease linearly from approximately 600 to 200 emu/cm³ with increasing x, whereas the Kᵤ values decrease slightly from approximately 15 to 10 Merg/cm³ 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.