On the role of spin-orbit splitting in magneto-optics (abstract only)On the role of spin-orbit split
On the role of spin-orbit splitting in magneto-optics (abstract only)On the role of spin-orbit split
复制标题
关于自旋轨道分裂在磁光中的作用（仅摘要）关于自旋轨道分裂的作用
DOI：
10.1088/0953-8984/15/5/322
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
J. Schoenes
中科院分区：
文献类型：
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作者：
J. Schoenes
光子与自旋的相互作用是通过自旋轨道耦合介导的。因此，磁性材料的磁光学至关重要地取决于所考虑的光学跃迁的初始和/或最终状态中的自旋轨道相互作用，这使得磁光学成为研究3d， 4f和5f材料中的自旋轨道耦合的非常有力的工具。本文将回顾过去30年来获得的一些最引人注目的结果（关于截至1990年的数据：Schoenes J 1991材料科学与技术卷3A金属和陶瓷的电子和磁性能主编）。R W Cahn， P Haasen和E J Kramer (Weinheim: VCH)p147)。迄今为止报道的最大法拉第旋转超过2×10 6度厘米-1。在单硫系铕EuS、EuSe和EuTe的薄膜中观察到它们具有4f7 （8S7/2）基态，即在初始态没有自旋轨道分裂。因此，大磁光信号的出现清楚地证明了在负责跃迁的最终状态中存在大的自旋轨道相互作用。线形分析表明，这一最终态由5d激发态与4f6激发态的耦合组成。Nd3S4是一个在初始状态和最终状态都具有自旋轨道耦合的系统的例子。反磁线形状有助于识别最终状态下的耦合，并可以确定自旋轨道参数。虽然CeSb的Kerr旋转的内在价值仍然存在争议，但无论如何，CeSb的Kerr旋转都是最大的。特别令人感兴趣的是从顺磁线形状到抗磁线形状的转变，当磁化强度从饱和降低。LaSe是另一个典型的例子。这里的初始态是非磁性的5d1态，磁光实验允许人们研究空的4f态。在所有这些镧系化合物中，russell - saunders耦合可以应用于初始态和终态。锕系化合物的最终状态不再是这样了。UO2薄膜的磁圆二色性和法拉第旋转测量表明，从5f2初始态激发的f电子的最终态接近于j-j耦合的5f1 -6d1态。必须采用一种不同的方法来解释单硫系铀的磁光数据。例如，在US的情况下，5f离域和f-d杂化太大，无法应用原子模型，并且需要复杂的能带结构计算来解释光谱。除了带间跃迁外，磁光学也被证明是研究自由载流子的有力工具。理论预测了两种不同类型的频率依赖性。这两种类型的示例将以TmSe和U3P4的数据形式呈现。CrPt3的特殊情况将在另一篇论文中讨论。
The interaction of photons with spins is mediated through spin-orbit coupling. Therefore, magneto-optics of magnetic materials depends crucially on the spin-orbit interactions in either the initial and/or the final state of the optical transition considered and this makes magneto-optics a very powerful tool for the study of spin-orbit coupling in 3d, 4f and 5f materials. This paper will review some of the most striking results obtained over the last 30 years (For the data up to 1990 see: Schoenes J 1991 Materials Science and Technology Vol 3A Electronic and Magnetic Properties of Metals and Ceramics eds. R W Cahn, P Haasen and E J Kramer (Weinheim: VCH)p147). The largest ever reported Faraday rotations exceed 2×10 6 deg cm-1. They have been observed in thin films of the europium monochalcogenides EuS, EuSe and EuTe, which have a 4f 7 ( 8S7/2) groundstate, i.e. no spin-orbit splitting in the initial state. The occurrence of the large magneto-optical signal is therefore clear evidence for a large spin-orbit interaction in the final state of the responsible transition. A line shape analysis shows that this final state consists of a coupling of the excited 5d electron with the remaining 4f 6 state. Nd3S4 is an example of a system with spin-orbit coupling in the initial as well as in the final state. The diamagnetic line shape helps to identify the coupling in the final state and the spin-orbit parameter can be determined. While the intrinsic value of the Kerr rotation of CeSb is still debated, agreement exists that in any case CeSb has the largest Kerr rotation. Of particular interest is the transition from a paramagnetic line shape to a diamagnetic line shape, when the magnetization is reduced from saturation. LaSe presents another archetypical example. Here the initial state is a non-magnetic 5d1 state and the magneto-optical experiment allows one to study empty 4f states. In all these lanthanide compounds Russel-Saunders coupling could be applied to the initial and final states. This is no longer the case for the final state in actinide compounds. Magnetic circular dichroism and Faraday rotation measurements on UO2 films evidence that the final state for the excitation of an f electron out of the 5f 2 initial state is near to a j-j coupled 5f 1-6d1 state. A different approach has to be made to interpret magneto-optical data for uranium monochalcogenides. In the case of US, for example, 5f delocalization and f-d hybridizations are too large to apply atomic models and sophisticated band structure calculations are needed to account for the spectra. Besides interband transitions, magneto-optics has also proven to be powerful for studying free carriers. Two different types of frequency dependencies have been predicted by theory. Examples of these two kinds will be presented in the form of data for TmSe and U3P4. The special case of CrPt3 will be discussed in a separate paper.