Spin-split Rashba bands have been exploited to efficiently control the spin degree of freedom of moving electrons, which possesses a great potential in frontier applications of designing spintronic devices and processing spin-based information. Given an intrinsic breaking of inversion symmetry and sizeable spin–orbit interaction, two-dimensional (2D) surface alloys formed by heavy metal elements exhibit a pronounced Rashba-type spin splitting of the surface states. Here, we have revealed the essential role of atomic orbital symmetry in the hexagonally warped Rashba spin-split surface state of the \(\sqrt 3 \times \sqrt 3 R30^0\) BiCu₂ monatomic alloy by scanning tunneling spectroscopy (STS) and density functional theory (DFT). From dI/dU spectra and calculated band structures, three hole-like Rashba-split bands hybridized from distinct orbital symmetries have been identified in the unoccupied energy region. Because of the hexagonally deformed Fermi surface, quasi-particle interference (QPI) mappings have resolved scattering channels opened from interband transitions of p_x,p_y (m_j = 1/2) band. In contrast to the s,p_z-derived band, the hexagonal warping is predominately accompanied by substantial out-of-plane spin polarization S_z up to 24% in the dispersion of p_x,p_y (m_j = 1/2) band with an in-plane orbital symmetry.

自旋分裂的Rashba波段已被用来有效地控制移动电子的自旋自由度，这在设计自旋电子器件和处理基于自旋的信息的前沿应用中具有巨大的潜力。考虑到固有的反演对称性破坏和自旋轨道相互作用，由重金属元素形成的二维（2D）表面合金表现出明显的表面态Rashba型自旋分裂。在这里，我们已经揭示了原子轨道对称在\（\ sqrt 3 \ times \ sqrt 3 R30 ^ 0 \） BiCu ₂的六边形翘曲Rashba自旋分裂表面状态中的重要作用。单原子合金通过扫描隧道光谱（STS）和密度泛函理论（DFT）。根据dI / dU光谱和计算出的能带结构，在空位能量区域中已经确定了三个由不同轨道对称性杂交而成的孔状Rashba分裂带。由于六角形变形的费米表面，准粒子干涉（QPI）映射已解析了从p _x，p _y（m _j  = 1/2）的带间跃迁打开的散射通道。与s ，p _z衍生的谱带相反，六角形翘曲主要伴随着显着的面外自旋极化S _z，其色散高达24％。 平面内轨道对称的p _x，p _y（m _j = 1/2）波段。