Crystallographic space group symmetry (CPGS) such as polar and nonpolar crystal classes have long been known to classify compounds that have spin-orbit-induced spin splitting. While taking a journey through the Brillouin Zone (BZ) from one k-point to another for a fixed CPGS, it is expected that the wavevector point group symmetry (WPGS) can change, and consequently a qualitative change in the texture of the spin polarization (the expectation value of spin operator $\vec{S}^{nk_{0}}$ in Bloch state $u(n,k)$ and the wavevector $k_0$). However, the nature of the spin texture (ST) change is generally unsuspected. In this work, we determine a full classification of the linear-in-$k$ spin texture patterns based on the polarity and chirality reflected in the WPGS at $k_0$. The spin-polarization vector $\vec{S}^{nk_{0}}$ controlling the ST is bound to be parallel to the rotation axis and perpendicular to the mirror planes and hence, symmetry operation types in WPGSs impose symmetry restriction to the ST. For instance, the ST is always parallel to the wavevector $k$ in non-polar chiral WPGSs since they contain only rotational symmetries. Some consequences of the ST classification based on the symmetry operations in the WPGS include the observation of ST patterns that are unexpected according to the symmetry of the crystal. For example, it is usually established that spin-momentum locking effect requires the crystal inversion symmetry breaking by an asymmetric electric potential. However, we find that polar WPGS can have this effect even in compounds without electric dipoles or external electric fields. We use the determined relation between WPGS and ST as a design principle to select compounds with multiple ST near band edges at different $k$-valleys. Based on high-throughput calculations for 1481 compounds, we find 37 previously fabricated materials with different ST near band edges.
Revealing sub-μm inhomogeneities and μm-scale texture in H2O ice at Megabar pressures via sound velocity measurements by time-domain Brillouin scattering
Investigation of the intrinsic hidden spin texture and spin-state segregation in centrosymmetric monolayer dichalcogenide: effectiveness of the electric-field approach
Polymorph-Tunable Spin Texture and Excitonic Structures in Monolayer WSi2P4
Hangzhou Dianzi University（杭州电子科技大学）；Southern University of Science and Technology（南方科技大学）；Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences（中国科学院大学杭州高等研究院）
Coupled spin-valley, Rashba effect and hidden persistent spin polarization in WSi$_2$N$_4$ family
实验成功地合成了新型二维材料MoSi $_2$ N $_4$和WSi $_2$ N $_4$，并从理论上预测了各种类似结构。在这里，我们报告的电子性质，特别关注的带分裂WA $_2$ Z $_4$（A=Si，Ge; Z=N，P，As），使用国家的最先进的密度泛函理论和多体微扰理论（在G $_0$ W $_0$和BSE的框架内）。由于反转对称性破缺和强的自旋轨道耦合效应，我们在第一布里渊区（BZ）的拐角处检测到耦合的自旋谷效应。此外，我们观察到立方和线性分裂带周围的$Γ$和M点，分别。有趣的是，面内镜像对称性（$σ_h$）和任意$k$点的约化对称性，强制持续自旋织构（PST）发生在整个BZ。我们诱导Rashba分裂通过打破$σ_h$通过一个面外电场（EEF）。W原子的反转非对称性在中心对称层状体材料中引入了隐藏的自旋极化。因此，自旋层锁定效应，即能量退化的相反自旋空间上分离的顶部和底部W层，已被确定。我们的低能$k.p$模型表明，沿M-K线的PST对EEF和层厚度是鲁棒的，使得它们适合于自旋电子学和谷电子学中的应用。
First-principles calculations of spin-split bands in chiral hybrid organic-inorganic perovskites ($R$/$S$-PEA)PbI$_3$ and ($R$/$S$-NEA)PbI$_3$
Institute for Materials Research, Tohoku University（东北大学物质材料研究所学）；Department of Applied Physics, Tokyo University of Science（东京科学大学应用物理系）；School of Advanced Science and Engineering, Waseda University（早稻田大学先进理工学研究院）
