First Principle Calculations on Structures and Magnetic Properties in Non-Stoichiometric Ni-Mn-Ga Shape Memory Alloys

Abstract

Change in cohesive energies in a non-stoichiometric Ni₉Mn₃Ga₄ alloy was calculated as a function of tetragonality, c/a, and compared with that in a stoichiometric alloy. A dip around c/a ≅ 0.97, which is seen in a stoichiometric alloy, disappears in the non-stoichiometric alloy, and a dip around c/a ≅ 1.23 become deeper than that in the stoichiometric alloy. These results are in good agreement with the influence of Ni concentrations on c/a in Ni-Mn-Ga alloys.