Phase structure and magnetic properties of Mn70Ga30-xSn (x = 5−30) alloy ribbons

In recent years, much attention has been paid to new rare-earth-free magnetic materials to avoid using the expensive and limited availability of rare earths. The Mn-based alloys with high magnetic anisotropy and Curie temperature well above room temperature have been regard as good candidate materials in spintronic devices and rare-earth-free magnets. In which, Mn-Ga binary compounds are such materials that exhibit a combination of various technologically important properties including high spin polarization, high perpendicular anisotropy, and high Curie temperature, multiple structures, temperature-induced phase transitions. An important feature of this kind of materials is that their structural and magnetic properties can be tuned with the changes of elemental compositions and annealing conditions to fit a specific practical application. On the other hand, the Mn₃Ga compound has the hexagonal structure of Ni₃Sn (D0₁₉) type similar to Mn₃Ge and Mn₃Sn, which are known to have the triangular antiferromagnetic spin structure with a small ferromagnetic moment in the c plane. In 1993, H. Niida reported the phase structure and magnetic properties of pseudobinary system Mn_3+δGa_1-xGe_x ingots. It was found that the D0₁₉-type structure is stable at 873 K in the whole composition range 0 ≤ x ≤ 1.0 with appropriate values of δ. In previous work, we reported the phase evolution, electric and magnetic properties of the annealed Mn_60+xGa_40-x (x = 0-15) melt-spun ribbons. In this work, Mn₇₀Ga_30-xSn_x (x = 5, 10, 15, 20, 30) melt-spun ribbons were prepared by using melt-spinning and subsequently annealing. The effects of Sn substitution for Ga on phase structure, Curie temperature T_C, magnetic properties of these annealed Mn-Ga-Sn ribbons have been investigated.