Orbital Rashba effect and its detection by circular dichroism angle-resolved photoemission spectroscopy
Orbital Rashba effect and its detection by circular dichroism angle-resolved photoemission spectroscopy
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轨道Rashba效应及其圆二色角分辨光电子能谱检测
DOI：
10.1103/physrevb.85.195401
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发表时间：
2011
影响因子：
3.7
通讯作者：
J. Han
中科院分区：
文献类型：
--
作者：
Jin;Choong H. Kim;Jun‐Won Rhim;J. Han
我们表明，通过紧束缚和第一性原理计算，电子的晶体动量k和非零轨道角动量（OAM）之间的一一对应是表面带的一个通用功能。OAM在动量空间中形成手征结构，就像Rashba模型中的自旋对应物一样，这是由于表面固有的反演对称性破缺，而不是自旋-轨道相互作用。圆二色性（CD）角分辨光电子能谱（ARPES）实验是一种有效的方法来检测这种新的顺序，我们推导出公式明确的CD-ARPES信号的存在OAM的能带结构。退化的p-和d-轨道带的情况下被认为是。PACS编号：在普通晶体固体中，电子自旋被淬灭，因为每个晶体动量k都是由自旋向上和自旋向下的电子组成的简并对。对于所谓的Rashba系统[1]，这种简并以一种有趣的方式被提升，在该系统中，带中给定的动量态只有一个与之相关的自旋态。在对称性的基础上，正如Rashba最初所论证的那样，在表面终止处固有的反转对称破缺（ISB）允许一个相互作用项，即Rashba项，其形式为HR = R z ·（k × k），涉及电子的自旋算符λ/2和动量k的耦合（我们设置~ λ 1）。动量空间中的手征自旋角动量（SAM）结构是Rashba Hamilton HR的直接结果[3，4]。
We show, by way of tight-binding and first-principles calculations, that a one-to-one correspondence between electron’s crystal momentum k and non-zero orbital angular momentum (OAM) is a generic feature of surface bands. The OAM forms a chiral structure in momentum space much as its spin counterpart in Rashba model does, as a consequence of the inherent inversion symmetry breaking at the surface but not of spin-orbit interaction. Circular dichroism (CD) angle-resolved photoemission (ARPES) experiment is an efficient way to detect this new order, and we derive formulas explicitly relating the CD-ARPES signal to the existence of OAM in the band structure. The cases of degenerate p- and d-orbital bands are considered. PACS numbers: Electron spins are quenched in ordinary crystalline solids in the sense that each crystal momentum k comes in degenerate pairs of spin-up and spin-down electrons. Such degeneracy is lifted in an interesting manner for the so-called Rashba system[1], in which the given momentum state in the band has only one spin state associated with it. Examples of Rashba-split bands are many by now[2]. On symmetry grounds, as Rashba originally argued, the inherent inversion symmetry breaking (ISB) at the surface termination allows an interaction term, the Rashba term, of the form HR = �Rˆ z · (k × �) involving the coupling of the electron’s spin operator �/2 and its momentum k (We set ~ ≡ 1). The chiral spin angular momentum (SAM) structure in momentum space follows as a direct consequence of the Rashba Hamiltonian HR[3, 4].