Electronic, structural, and magnetic properties of the quaternary Heusler alloy NiCoMnZ (Z=Al, Ge, and Sn)

The electronic, magnetic, and structural properties of the Heusler alloys NiCoMRZ (Z=Al, Ge, and Sn) have been investigated both theoretically and experimentally. NiCoMnGe and NiCoMnSn have ordered cubic Heusler structure (with a possible disorder between Ni and Co), while NiCoMnAl has a B2 type disordered Heusler structure with random occupancy between Mn and Al atom at their crystallographic sites. Electronic structure calculation shows that NiCoMnGe and NiCoMnSn are normal ferromagnets, whereas NiCoMnAl is nearly half metallic (similar to 100% spin polarization) in nature with its magnetic moment close to an integer value following the Slater-Pauling rule. Ab-initio calculations show similar to 56% and similar to 60% spin polarization for NiCoMnGe and NiCoMnSn, respectively. Magnetization measurements show all the three compounds have a high Curie temperature (> 583 K). (C) 2014 Elsevier B.V. All rights reserved.