Effect of isoelectronic substitution on phase transition and magnetic properties of Ni₅₇Mn₁₈Ga_25-xIn_x (0≤x le;8) alloys with Ni excess

Effect of isoelectronic substitution of In for Ga on the phase transition and magnetic properties was studied in Ni₅₇Mn₁₈Ga_25-xIn_x (0 ≤ x ≤ 8) alloys. With the increasing In content, the room-temperature phase structure evolved from tetragonal martensite to cubic austenite. The martensitic transformation temperatures were significantly decreased by the substitution of In for Ga, but the austenitic Curie temperature was only slightly decreased. Especially, both thermal and isothermal magnetization measurements revealed that the Curie temperature and saturation magnetization of the martensite were independent on the isoelectronic substitution. The results were discussed by considering the phase structures and the atomic interactions.