In this review, we summarize the recent progress in the understanding of the spin-polarized electronic states in two-dimensional (2D) atomic layer materials (ALMs) formed on solid surfaces. The spin-polarized electronic states caused by the combination of spin-orbit coupling (SOC) with broken spatial inversion symmetry along the surface normal direction is one of the most exotic phenomena that appears on ALMs formed on solid surfaces as well as clean solid surfaces. The so-called Rashba-Bychkov (RB) effect that arises from the potential gradient induced by broken inversion symmetry was believed to be the main origin of these spin-polarized electronic states. However, the spin texture of most ALMs are different from that caused by the ideal RB effect. Due to the high impact of the spin-polarized electronic states of 2D materials in not only spin-related fundamental science but also in applications since they are the key concepts to realize future semiconductor spintronics devices, much efforts have been made to elucidate the origin of these peculiar spin textures. So far, the deviations in spin texture from the ideal one have been attributed to be induced by perturbation, such as entanglement of spin and orbital momenta. In this review, we first illustrate how the symmetry of the ALM’s atomic structure can affect the spin texture, and then introduce that various spin textures, ranging from the RB-type and symmetry-induced type to spin textures that cannot be explained based on the origins proposed so far, can be simply induced by the orbital angular momentum. This review aims to provide an overview on the insights gained on the spin-polarized electronic states of ALMs and to point out opportunities for exploring exotic physical properties when combining spin and other physics, e.g. superconductivity, and to realize future spintronics-based quantum devices.

在这篇综述中，我们总结了在固体表面上形成的二维（2D）原子层材料（ALM）中自旋极化电子态的理解的最新进展。由自旋轨道耦合 (SOC) 与沿表面法线方向破坏的空间反演对称性相结合引起的自旋极化电子态是在固体表面以及干净的固体表面上形成的 ALM 上出现的最奇特现象之一。由破坏的反转对称性引起的电位梯度引起的所谓 Rashba-Bychkov (RB) 效应被认为是这些自旋极化电子态的主要来源。然而，大多数 ALM 的自旋纹理与理想 RB 效应引起的自旋纹理不同。由于二维材料的自旋极化电子态不仅在与自旋相关的基础科学中而且在应用中都有很大的影响，因为它们是实现未来半导体自旋电子器件的关键概念，因此已经做出了很多努力来阐明这些奇特的旋转纹理。到目前为止，自旋纹理与理想纹理的偏差被认为是由扰动引起的，例如自旋纠缠和轨道动量。在这篇综述中，我们首先说明 ALM 原子结构的对称性如何影响自旋织构，然后介绍各种自旋织构，从 RB 型和对称诱导型到无法解释的自旋织构到目前为止提出的起源，可以简单地由轨道角动量诱导。