Theory of Electronic Structure and Magnetic Phase Diagram of Intermetallic Compounds

为了弄清各种过渡金属化合物d电子的性质，无论是定域的还是巡回的，并解释所观察到的磁性，了解每种化合物的电子能带结构是有用的。在此之前，我们对NiAs型化合物、1T型和2H型层状化合物及其插层化合物以及M=锌、镓、锡的Mn3mc型化合物进行了系统的能带计算。通过计算键级，阐明了这些化合物的成键性质。此外，根据Moriya发展的自旋涨落理论，考虑到每种化合物的态密度的特征行为，对NiAs型化合物中观察到的反常磁性进行了解释。近两年来，我们计算了立方钙钛矿型化合物、Mn4N和Mn4C、Cu2Sb型化合物、Mn2As、Mn2Sb、Cr2As、Fe2As、Cu2Sb、MnAlGe、MnGaGe、MnGe和Cu3Au型化合物的电子能带用于非磁性和磁性(铁氧体或反铁氧体)状态。用自洽APW和LAPW方法计算了所有化合物的磁矩，计算结果与观测值吻合较好。此外，计算得到的Mn2Sb、MnAlGe和Cr2As的态密度的总体特征与光电子能谱和逆光电子能谱有很好的一致性。

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.