Ab initiostudies of effect of copper substitution on the electronic and magnetic properties of Ni2MnGa and Mn2NiGa

Abstract

Using first-principles density functional theory based calculations, we study systematically the effect of medium to large Cu substitution at the Mn, Ga as well as Ni sites on the geometric, bulk mechanical, electronic, and magnetic properties of Ni${}_{2}$MnGa and Mn${}_{2}$NiGa. The calculations have been carried out for possible austenite and martensite phases using a supercell approach. Partial Cu substitutions at Mn and Ga sites show promises in terms of the electronic and magnetic properties for both Ni${}_{2}$MnGa and Mn${}_{2}$NiGa alloys from an application point of view. Our calculations predict that for certain partial substitutions, the austenite to martensite transition temperature is likely to increase and the system remains magnetic in nature. On the other hand, a significantly large amount of Cu substitution at the Ni site seems to stabilize the austenite phase in both of these alloy systems rendering a martensite transition unlikely. Interestingly, the overall trend in the changes in the structural, bulk mechanical, electronic, and magnetic properties of these two different types of alloy systems, Ni${}_{2}$MnGa and Mn${}_{2}$NiGa, as a result of substantial Cu substitution in all the three different sites, is found to be the same.