Lattice Distorition and Electronic Structure of Ferromagnetic Transition Metals and Alloys

点击翻译按钮获取中文摘要

The main purpose of the present project is to study the relation between the electronic structure and the lattice of transition metals and alloys. Several different approaches have been tried: 1. Electronic structure of transition metal alloy are investigated by use of the KKR-CPA method to study the microscopic origin of the martensitic transformation which often is observed for these alloys. The following results are obtained: (1) By calculating the response of the lattice to the external force, it is shown that an fcc-fct instability is expected for FePd. (2) The present first-principle calculation well reproduces the so-called Slater-Pauling curve of magnetic moment of 3d allyoys. (3) The lattice constants of these alloys are determined by minimizing the total energy: a magnetic and a chemical contributions to the cohesive properties are investigated.2. The electronic structure of Mn in the multiple spindensity-wave (MSDW) state is investigated by the tight-binding model. The relation between the number of d electrons and the MSDW state is discussed and the concentration dependence of the MSDW state of MnFe alloys are explained by taking account of the tetragonal distortion. Also to discuss such complicated systems from the first-principle, LMTO computer code is developed. As a typical example the lattice constant of the antiferromagnetic Mn is performed: the calculation of the MSDW state as well as the tetragonally distorted systems are now in progress.3. The lattice distrotion which is compatible with the possible magnetic structure is discussed by use of the Landau's expansion of free energy and the phase diagram in the plane spanned by temperature and composition is constructed. Phase diagrams which appear for Mn alloys are explained systematically by taking account of the coupling between three independnt spin-density-waves and the lattice distortion. Also explained is the two tetragonal phases appearing in CsCl-type AuMn.