Structural and magnetic properties of XMnSb/PtMnSb Clb Heusler alloy superlattices (X=Ni, Cu)

We have grown superlattices based on the C1(b) Heusler alloys PtMnSb, CuMnSb and NiMnSb between 200-500 degrees C on Al2O3 (0001). X-ray diffraction (XRD) indicates (111) oriented ordered structures for growth at 300 degrees C. Higher deposition temperature leads to interdiffusion, loss of the multilayer structure and appearance of extra phases. Growth at 200 degrees C slightly reduces the intermixing but also reduces the quality of the crystal structure. For PtMnSb/CuMnSb, we found an enhancement of the saturation magnetization compared to equivalent PtMnSb single layer films and a CuMnSb spacer thickness dependence of the squareness of the M(H) loops suggestive of interlayer coupling. Short periodicity NiMnSb/PtMnSb superlattices show an in-plane magnetic easy axis, but correction for shape anisotropy indicates a tendency for perpendicular anisotropy.