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Energy Band Calculation of the Compounds with Rare Earth and Transition metals

稀土和过渡金属化合物的能带计算

基本信息

批准号：
61540224
负责人：
ASANO Setsuro
金额：
$ 0.7万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

项目摘要

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.

1. 在LSD近似的框架下，通过LMTO-ASA计算系统研究了Laves相化合物AB_2（A=Y,Zr,Nb;B=Cr,Mn,Co,Fe）的电子结构。将计算出的顺磁态、铁磁态和反铁磁态的总能量与C14或C15结构进行比较，理论预测与有关晶体结构和磁性稳定性的实验非常吻合。对于非磁性状态，晶体结构几乎由B原子决定：Cr、Co或Ni有利于C14结构，Mn或Ni有利于C15结构。当A原子按Y、Zr、Nb的顺序变化时，晶格间距减小，B原子的磁性按此顺序变弱，导致TiFe_2、NbFe_2或Sc_<1-x>Ti_xFe_2等铁拉夫斯相化合物的磁性呈现多彩的行为。在Mn Laves相化合物中，唯一具有磁性的是YMn_2，该计算合理地解释了YMn_2在反铁磁状态下的反常体积变化。2．通过LSD-LMTO-ASA计算系统研究了R_2Fe_ 17 B(R=Y,Ce,Nd,Gd)的电子结构。每个原子位点的磁化强度（30 _B/FU）和磁矩的计算结果与实验吻合良好。同时还研究了RFe_2、RFe_5和r_2Fe_<17>(R=Y,Ce,Gd)的电子结构。 3．采用LSD-FLAPW方法计算了LaB_6和CeB_6的电子结构和正电子湮没剖面，并与实验进行了比较。 4．通过 LSD-LMTO-ASA 计算研究了 Si/二硅化物界面的电子结构。