Magneto--Optical Ellipsometry on Ni$_{2}$MnIn and NiMnIn Heusler Alloys

We use generalized magneto-optical ellipsometry [1,2] for measurements of the complete dielectric tensor of Ni$_{2}$MnIn [3] and NiMnIn Heusler alloys in the energy range from 1.6 eV to 5.5 eV and in the temperature range from 50 K to 450 K. Generalized magneto-optical ellipsometry allows the investigation of spin-polarized states and to understand the coupling between spin and charge degrees of freedom. We show differences in the metallic behavior of the semi-Heusler alloy NiMnIn and the full-Heusler alloy Ni$_{2}$MnIn related to the half-metallic ferromagnetism of the latter one. The polycrystalline Ni$_{2}$MnIn and NiMnIn films were co-evaporated from two independent sources of Ni and MnIn on a Si(100) substrate under UHV conditions. The Ni$_{2}$MnIn alloy exhibits the ordered L2$_{1}$ crystalline structure and the NiMnIn alloy has a C1$_{b}$ structure. [1] A. Berger and M. Pufall, Appl. Phys. Lett. \textbf{71}, 965 (1997) [2] R. Rauer, G. Neuber, J. Kunze, J. B\"{a}ckstr\"{o}m, and M. R\"{u}bhausen, Rev. Sci. Instr. \textbf{76}, 023910 (2005){\}} [3] S. von Oehsen, J.M. Scholtyssek, C. Pels, G. Neuber, R. Rauer, M. R\"{u}bhausen, and G. Meier et al., JMMM \textbf{290}, 1371 (2005){\}}