First-principle investigations of the magnetic properties and possible martensitic transformation in Ni2MnX (X=Al, Ga, In, Si, Ge and Sn)

•Both austenitic and martensitic Ni2MnX alloys are found to be ferromagnets.•The energy difference between the martensitic and austenitic phases is negligible.•The total moment in martensitic phase is close to corresponding to austenitic phase.

The magnetic and electronic properties of Ni2MnX (X=Al, Ga, In, Si, Ge and Sn) Heusler alloys have been studied by using the first-principle projector augmented wave potential within the generalized gradient approximation. The possible non-modulated martensitic transformation in these six alloys has been investigated. Both austenitic and martensitic Ni2MnX (X=Al, Ga, In, Si, Ge and Sn) Heusler alloys are found to be ferromagnets. In martensitic phase, the energies minimum occurs at c/a=0.99 for Ni2MnX (X=Al, In, Ge and Sn), and the energy minimum occurs at c/a=1.02 for Ni2MnSi. But there is a negligible energy difference ΔE (<6 meV/cell) between the austenitic and martensitic phases for each alloy. Meanwhile, around c/a=1, an anomaly is observed in the E-c/a curve, which is related to a very slightly tetragonal distortion trend in Ni2MnX (X=Al, In, Si, Ge and Sn). The energy difference ΔE between the austenitic and martensitic phases for Ni2MnGa is as large as 99 meV/cell, so it is more likely to realize martensitic transformation in it.