Origin of unusual properties in the ferromagnetic Heusler alloy Ni-Mn-Sn: A first-principles investigation

The martensitic phase transformation temperatures in the Ni-Mn-Sn Heusler alloys increase with the number of valence electrons per atom; however, when Mn atoms are substituted by Fe, Co or Cu atoms, the systems show anomalous behaviors. In addition, large magnetization changes are observed in these alloys. To understand the unusual properties, the phase transitions in Ni-Mn(Z)-Sn (Z = 3d transition metals) are studied using first-principles calculations. It is found that the changes in the magnetic configuration are responsible for the unusual properties observed.