Shinya Wakoh

Band Structure of Ferromagnetic Iron Self-Consistent Procedure

The band structure of ferromagnetic iron is calculated by the Greens function method. The crystal potential is determined self-consistently for both spin-up and spin-down electrons, respectively. The theoretical results are compared with experimental results: the electronic specific heat, the magnetoresistance, de Haas-van Alphen effect and the scattering form factors. The agreement between the seems to be satisfactory.

Band Structure of Metallic Copper and Nickel by a Self-Consistent Procedure

Band structure of metallic copper and nickel are calculated by a self-consistent procedure. A self-consistent potential is constructed by a modified Hartree-Fock-Slater approximation. The general properties of the bands are in good agreement with those obtained previously. The band structure of Ni in a ferromagnetic state is evaluated. The exchange splitting energy for d-like electrons is estimated as about 0.07 Ry, while for s- and p-like electrons as 0.015 Ry. The theory suggests that there exists a neck on the Fermi surfaces of both up- and down-spin electron bands.

Fermi Surface of Ni

The energy band structure of ferromagnetic nickel is evaluated by the Greens function method and the interpolation method developed by Slater and Koster. The effective potential is suitably chosen so as to give a reasonable fit with the results of recent experiments about the Fermi surface.

Energy Band Structure of Nickel

Energy band structure of Nickel is investigated by the modified tight-binding approximation and the Greens function method. Proper l -dependent potentials are used for computation. The general character of the 3d-bands is quite similar to that in Cu. The total width of the 3d-bands is estimated as 0.304 ry by TBA, and 0.314 ry by GFM.

State-Dependent Potentials in Metallic Vanadium and Chromium

First, the electronic structures of metallic vanadium and chromium are investigated in the framework of the local self-consistent band theory with the Xα-potential and the modified Wigner-Seitz potential and the results are compared with available experiments. The agreement is generally good, but there remains some discrepancy in the dimensions and shape of the Fermi surfaces. Then the state-dependent potential is introduced, that is, the different potential for the d e - and dγ-states. The calculated results are in better agreement with the experimental results such as Fermi surface, electronic specific heat coefficient γ, d e population of 3d electrons and so on. The origin of difference in the potentials for the d e - and dγ-states seems to by mainly ascribed to the difference in the effective intra-atomic exchange for the d e - and dγ-states. The form factor values are also calculated and the are in good agreement with experiments.

Band Structure of Cobalt by a Self-Consistent Procedure

The band structure of h.c.p. cobalt is calculated self-consistently by using Greens function method. The calculation gives the density-of state curve for the paramagnetic state, the Fermi energy for both spin bands, the shape of Fermi surfaces. The exchange splitting energy Δ E is estimated to be 1.71 eV from the density-of-states and the Bohr magneton number, but it is estimated as about 1.1 eV from the other properties, particularly from the photoemission data. This difference is presumably due to uncertainties in the potential which, when corrected, should cause the s -band to be lower in energy by about 0.5 eV.

Internal Field and Isomer Shift of Metallic Iron and Nickel

Internal field of ferromagnetic iron is evaluated on the basis of the self-consistent and spin-dependent band structure, which was calculated by the authors. The number of the 4 s electrons, (that is, the s component of the s -, p - and d - hybridized conduction bands), and the number of unpaired 4 s electrons are determined by the band wave-functions. The wave functions of the core electrons are spin-dependent because of the polarization of the conduction electrons. They are determined by the variational method in the frame of the unrestricted Hartree-Fock scheme. The calculated value of the Fermi contact term χ of iron is -4.415, while the observed value is -3.6. The agreement between theory and experiment is reasonable. A similar calculation of the Fermi contact term of nickel gives the value -5.8, while the observed value is -6.75. The isomer shift of Fe 57 is also calculated.

Band Theory of Super-Lattice CoFe

Results of numerical calculations of the band structure of the super-lattice CoFe are presented. The calculations are carried out according to the Greens function method and the augmented plane wave method. Several E ( k )-curves and a density-of-states curve are shown together with the numerical tables. The general character of the bands agrees well with prediction given by Mott.

Compton Profiles of Metallic Vanadium

Compton profiles of metallic vanadium are calculated by KKR method. The potential is carefully selected so as to reproduce the measured Fermi surfaces and to fit the experimental X-ray scattering factors. The theoretical average profile is in good agreement with the profiles observed by Paakkari et al. and by Phillips. The calculated degree of the anisotropy in the profiles is in qualitative agreement with that observed by Terasaki et al. The shape of the Fermi surfaces must be taken into account to explain the observed anisotropy.

Compton Profiles due to the Band Electrons in Metallic Vanadium and Chromium

The Compton profiles due to the band electrons in vanadium and chromium are calculated from the wave functions obtained by APM method. The results are compared with other theoretical works and available experiments. The observed structures on the Compton profiles are well interpreted from the band theoretical point of view.