Structural and magnetic properties of a new and ordered quaternary alloy MnNiCuSb (SG: F 4¯3m)

• A new crystallographically ordered quaternary Heusler alloy MnNiCuSb has been synthesized.
• It crystallizes in LiMgPdSb type structure with F  4¯3m space group.
• MnNiCuSb is a ferromagnet with a high TC~690 K and magnetic moment of 3.85 µB/f.u.

We have synthesized a new crystallographically ordered quaternary Heusler alloy, MnNiCuSb. The crystal structure of the alloy has been determined by Rietveld refinement of the powder X-ray diffraction data. This alloy crystallizes in the LiMgPdSb type structure with F  4¯3m space group. MnNiCuSb is a ferromagnet with a high TC~690 K and magnetic moment of 3.85 µB/f.u. Besides this we have also studied two other off-stoichiometric compositions; one Cu rich and the other Ni rich (MnNi0.9Cu1.1Sb and MnNi1.1Cu0.9Sb) which are also ferromagnets. It must be stressed that MnNiCuSb is one of the very few known, non-Fe containing quaternary Heusler alloys with 1:1:1:1 composition.