| Budget Amount *help |
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1988: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1987: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1986: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
1. The electronic structures of Laves phase compounds AB_2 (A=Y,Zr,Nb;B=Cr,Mn,Co,Fe) were investigated systematically by the LMTO-ASA calculation within the framework of the LSD apprpximation. Comparing the calculated total energy for hypothetical para-, ferro- and antiferromagnetic state with the C14 or C15 structure, the theoretical predictions are in good agreement with the experiments concerning the stability of the crystal structure and the magnetism. For the nonmagnetic state, the crystal structures are almost determines by the B atom: Cr, Co or Ni favours the C14 and Mn or Ni favoures the C15 structure. When the A atom changes in the order Y, Zr and Nb, the lattice spacing decreases and the magnetism of the B atom becomes weak in this order, which leads to the colorful behaviours of the magnetism in iron Laves phase compounds such as TiFe_2, NbFe_2 or Sc_<1-x>Ti_xFe_2. In Mn Laves phase compounds, the only magnetic one is YMn_2, whose anomalous volume change in the antiferromagnetic state was reasonably explained by this calculation.
2. The electronic structures of R_2Fe_<17>B(R=Y,Ce,Nd,Gd) were investigated systematically by the LSD-LMTO-ASA calculation. The calculated results of the magnetisation (30 _B/FU) and the magnetic moments at each atomic sites were in good agreement with the experiments. The electronic structures of RFe_2, RFe_5 and r_2Fe_<17> (R=Y,Ce,Gd) were also investigated in the same line.
3. The electronic structures and the positron-annihilation-profiles of LaB_6 and CeB_6 were calculated by the LSD-FLAPW method and compared with the experiments.
4. The electronic structures of Si/Disilicides interfaces were investigated by the LSD-LMTO-ASA calculation.
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