Ce_(1-x)Y_xFe_2的电子结构和磁性质

ELECTRONIC STRUCTURE AND MAGNETIC PROPERTIES OF Ce_(1-x)Y_xFe_2 COMPOUNDS

用第一性原理计算了Ce1-xYxFe2 电子结构和自旋磁矩值 ,解释了Y的替代对CeFe2 中磁性和磁致伸缩的影响 .通过对Stoner作用参量的计算 ,表明CeFe2 弱的铁磁性的提供者主要是Fe,且Ce的局域铁磁性是不稳定的 .计算结果表明体积的变化对Fe的局域位的磁性影响较大 ,但并不很显著的影响Ce位的态密度和磁性质 .Y原子对CeFe2 中Ce的替代对电子结构产生了两个方面的影响 :费米面的下降和尖锐的 4f能级的降低 .费米面的下降使Ce的 4f电子更加退局域 ,而尖锐的 4f能级的降低则使得Ce的 4f电子的局域化程度增强 .这两个相互竞争的过程使得Ce的价态呈现出波动性的特性 .

Electronic structure and spin moment of Ce1-xYxFe2 are calculated using a fully self-consistent discrete variational method within the local density framework. These results are used to explain the effect of magnetic properties and magnetostriction on Ce-site substituted by Y in CeFe2. Stoner action obtained indicates that the local Fe magnetic moment provides mainly the weak ferromagnetism from CeFe2, and Ce-site local moment is unstable. The local magnetic moment of Fe-site depends strongly on the volume change of the investigated system, which does not noticeably affect the density of state and magnetic properties. The Ce-site substituted by Y results in two effects on electronic structure, that is, the descent of Fermi surface and the descent of the main peak of Ce 4f energy level. The competition of the two descents results in the fluctuation of Ce valence.