Spin-Resolved Spectroscopy and Magnetic Dichroism of Intermetallic Ferromagnets

利用高能光谱学研究了铁磁性金属间化合物的电子态。利用圆偏振入射光和自旋分析，得到了磁性和非磁性原子的局部自旋和轨道矩等磁性信息。对Nd_2Fe_<14>B进行了Fe 2p XAS和Nd 3d和4d XAS的MCD测定。在Fe 2p XAS中的MCD表明，3d电子的<Lz>/<Sz>估计为0.1左右。Nd三维和4d XAS中MCD的实验与计算对比表明，Nd的4f电子具有很强的原子性质。发现CoPt_3的MCD线形状非常异常，使用包含Fano效应的聚类模型可以半定量地解释这一点。分析表明，p5d电子的<Lz>/<Sz>约为0.6。这项工作首次证明，即使存在强烈的法诺效应，也可以通过分析MCD来估计轨道矩。co_2中Co 2p XAS的MCD表明，尽管Co 3d电子具有低自旋特性，但Co 3d电子的<Lz>/<Sz>约为0.2。这可以通过使用考虑到三维电子之间静电相互作用引起的多重分裂的簇模型计算初始状态来定性地再现。通过分析表明，轨道矩的来源是静电相互作用的非对角线元素与自旋轨道相互作用之间的相互作用。另一方面，在s3p XAS中发现了小而清晰的MCD。起源被认为是由于与Co - 3d电子杂化导致的S - 3d部分态密度的交换分裂。

We investigated the electronic states of the ferromagnetic intermetallic compounds using high-energy spectroscopy. Magnetic information as local spin and orbital moment on magnetic and non-moagnetic atoms were yielded using circularly polarized incident light and by performing spin-analysis.MCD in Fe 2p XAS and Nd 3d and 4d XAS were taken for Nd_2Fe_<14>B.MCD in Fe 2p XAS shows that <Lz>/<Sz> of the 3d electrons is estimated to be as large as about 0.1. Comparison between experiments and calculations of MCD in Nd 3d and 4d XAS shows that the 4f electrons of Nd have a very atomic character.A very anomalous MCD line shape is found for CoPt_3, which is semi-quantitatively explained using a cluster-model incorporated with Fano effect. This analysis shows that <Lz>/<Sz> of Pt 5d electron is about 0.6. This work demonstrated for the first time that the orbital moment can be estimated by analysing the MCD even if a stron Fano effect is present.MCD in Co 2p XAS in CoS_2 shows that <Lz>/<Sz> of Co 3d electrons is about 0.2, in spite of the low-spin character of the Co 3d electrons. This can be reproduced qualitatlively by a calculation of the initial state using a cluster model taking into account the multiplet splitting due to the electrostatic interaction between the 3d electrons. Through this analysis, the origin of the orbital moment is shown to be the interplay between the non-diagonal element of the electrostatic interaction and the spin-orbit interaction. On the other hand, small but clear MCD was found for S 3p XAS.The origin is considered to be the exchange splitting of the S 3d partial density of state due to the hybridization with the Co 3d electrons.