Hsu Ming-Chien, Yao Liang-Zi, Tan Seng Ghee, Chang Ching-Ray, Liang Gengchiau, Jalil Mansoor B A
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore. Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
J Phys Condens Matter. 2018 Jul 18;30(28):285502. doi: 10.1088/1361-648X/aac86f. Epub 2018 May 29.
The Rashba effect gives rise to the key feature of chiral spin texture. Recently it was demonstrated that the orbital angular momentum (OAM) texture forms the underlying basis for Rashba spin texture. Here we solve a model Hamiltonian of a generic p-orbital system in the presence of crystal field, internal spin-orbit coupling (SOC) and inversion symmetry breaking (ISB), and demonstrate, in addition to OAM and spin texture, the existence of orbital projection (OP) of the spin texture in a general Rashba system. The unique form of the OP pattern follows from the same condition for the existence of chirality of the spin texture. From the analytical results, we obtained the spin polarization as a function of parameters such as the SOC strength, crystal field splitting and degree of ISB, and compare them with those from numerical solutions and ab initio calculations. All three methods yield highly consistent results. Our results suggest means of external modulation, and elucidate the multi-orbital nature of the Rashba effect and the underlying OP of the spin texture. The understanding has potential applications in fields such as spin-orbitronics that requires delicate control between orbital occupancy and spin momentum.
Rashba效应产生了手性自旋纹理的关键特征。最近有研究表明，轨道角动量（OAM）纹理构成了Rashba自旋纹理的基础。在此，我们求解了一个存在晶体场、内禀自旋轨道耦合（SOC）和反演对称性破缺（ISB）的一般p轨道系统的模型哈密顿量，并证明，除了OAM和自旋纹理外，在一般的Rashba系统中还存在自旋纹理的轨道投影（OP）。OP图案的独特形式源于自旋纹理手性存在的相同条件。从分析结果中，我们得到了作为SOC强度、晶体场分裂和ISB程度等参数函数的自旋极化，并将其与数值解和从头计算结果进行了比较。这三种方法都给出了高度一致的结果。我们的结果提出了外部调制的方法，并阐明了Rashba效应的多轨道性质以及自旋纹理的潜在OP。这一认识在诸如自旋轨道电子学等需要在轨道占据和自旋动量之间进行精细控制的领域具有潜在应用。
