Ab initio calculations of structural and magnetic properties of Ni-Co-Mn-Cr-Sn supercell

The crystal lattice parameters, tetragonality degree, magnetic moments, magnetic exchange parameters in the Ni7Co1Mn5Cr1Sn2 Heusler alloy are investigated by ab initio calculations and supercell approach. Three 16-atom supercells with different atomic configurations relative to Cr atom are considered. On the one side, if the Cr atom is surrounded by one Sn and two Mn nearest neighbors the respective supercell in austenite is found to be favorable with compared to other ones. On the other side, the supercell consisting three nearest Mn atoms against Cr atom is more stable in martensite. Total magnetic moment of all supercells is almost the same and it increases linearly with increasing lattice parameter. Exchange interactions between Cr and Mn atoms depend strongly on the atom distribution. The strong antiferromagnetic coupling between nearest Cr-Mn pairs is found.