Effect of the main-group elements on the electronic structures and magnetic properties of Heusler alloys Mn₂NiZ (Z=In, Sn, Sb)

The magnetic properties and electronic structure of Mn₂NiZ (Z=In, Sn, Sb) have been studied. The magnetic structure of these alloys is mainly determined by the main-group element Z instead of the distance between the Mn atoms. Electronic structure calculations suggest that Mn₂NiIn and Mn₂NiSn are both ferrimagnets with antiparallel alignment between the Mn moments. But this antiferromagnetic coupling is weakened by the increasing number of valence electrons of the Z atoms. When it comes to Mn₂NiSb, a ferromagnetic coupling between the Mn atoms is observed. Mn₂NiSn and Mn₂NiSb have been synthesized successfully. Their M_s at 5 K agree well with the theoretical value.