Theory of Electronic Structure and Magnetic Phase Diagram of Intermetallic Compounds

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To clarify the nature of the d-electrons, either localized or itinerant, various transition-metal compounds, and to explain the observed magnetic properties, it is useful to know the electronic band structure for each compound.Previously we have made systematic band calculations for NiAs-type compounds, 1T-type and 2H-type layered compounds and their intercalation compounds, and Mn_3MC-type compounds with M=Zn, Ga, Sn. The nature of bonding in these compounds were elucidated by calculating the bond orders. Furthermore, anomalous magnetic properties observed in NiAs-type compounds, such as MnAs, CoAs, and FeAs, have been explained on the basis of spin fluctuation theory developed by Moriya, by taking account of characteristic behavior of the density of states obtained for each compound.During recent two years, we have calculated electronic bands of cubicperovskite-type compounds, Mn_4N and Mn_4C, Cu_2Sb-type compounds, , Mn_2As, Mn_2Sb, Cr_2As, Fe_2As, Cu_2Sb, MnAlGe, MnGaGe, MnZnGe, and Cu_3Au type compounds FePt_3, FePd_3, for non-magnetic and magnetic(ferro or antiferro)states. Self-consistent APW and LAPW methods are used.The magnetic moments calculated for all compounds are in good agreement with observed values. Furthermore, the overall feature of the calculated density of states of Mn_2Sb, MnAlGe and Cr_2As shows good correspondence with the spectrum observed by photoemission and inverse photoemission measurement.