COMPUTATIONALLY BASED EXPLANATION OF THE PECULIAR MAGNETOOPTICAL PROPERTIES OF PTMNSB AND RELATED TERNARY COMPOUNDS

The magneto-optical (MO) spectra of 15 ternary ferromagnetic compounds are investigated on the basis of local-density band-structure calcula tions. The key material of interest in this study is PtMnSb, for which the MO Ken spectra are unusually large and quite different from that of, e.g., the isoelectronic compounds NiMnSb and PdMnSb. First we show that the spectral differences between NiMnSb, PdMnSb, and PtMnSb can be fully understood from their relativistic electronic structure. Furt her, we investigate the following ternary ferromagnetic compounds: PtM nSn, PtCrSb, PtFeSb, Pt2MnSb, Co(2)sHfSn, NiMnAs, PdMnAs, PtMnAs, RuMn As, PtMnBi, BiMnPt, and PtGdBi. Within the total group of alloys, we s tudy the MO spectra of PtMnSb in relationship to the spin-orbit coupli ng strength; the magnitude of the 3d-magnetic moment; the degree of hy bridization in the bonding; the half-metallic character, or, equivalen tly, the Fermi-level filling of the band structure, the intraband plas ma frequency; and the influence of the crystal structure. We find that these characteristics form a unique combination in PtMnSb leading to its outstanding MO I(err spectra. None of the other compounds can matc h up to PtMnSb in this respect. For the compounds NiMnAs, PdMnAs, PtMn As, and, particularly, RuMnAs, whose MO spectra are not measured as ye t, we predict Kerr spectra which look promising for ultraviolet laser light recording applications.