AI 中文总结
本研究通过角分辨光电子能谱结合模型计算，揭示了过渡金属吸附对拓扑晶体绝缘体Pb₁₋ₓSnₓSe不同晶面表面电子结构的调控机制，为自旋电子与量子器件研发提供新平台。
AI 中文摘要
拓扑绝缘体/磁性金属（TI/MM）界面的电子结构对于理解奇特的自旋相关现象以及实现先进的自旋轨道电子器件至关重要。本文中，我们采用在拓扑晶体绝缘体（TCI）Pb$_{1-x}$Sn$_{x}$Se表面沉积亚单层过渡金属（TM）的模型体系，通过角分辨光电子能谱（ARPES）系统绘制了表面电子结构随覆盖度的变化规律。对于极性（111）Pb$_{1-x}$Sn$_{x}$Se表面，我们观察到狄拉克拓扑表面态（TSS）与拉什巴分裂表面态（RSS）共存，这是由反演对称性破缺、表面能带弯曲和轨道角动量效应共同作用导致的。特别地，我们证明可以获得非常大的拉什巴分裂，并且拉什巴参数（$α_R$）可根据TM吸附原子的类型和覆盖度，在0到3.5 eV·$\boldsymbol{\r{A}}$的极宽范围内调控。模型哈密顿量计算证实了实验结果，并揭示这种共存现象源于TM引起的表面掺杂对TSS的填充。相比之下，对于具有双狄拉克锥拓扑表面态的非极性（001）表面，反演对称性得以保持，因此不会出现拉什巴分裂表面态。取而代之的是，表面电荷不平衡会引发双狄拉克锥波函数的退相，从而减小它们在动量空间中的间距。这些发现阐明了拓扑绝缘体/过渡金属界面上发生的新奇现象，为未来的自旋电子学和量子器件提供了一个通用平台。
英文摘要
The electronic structure of topological insulator/magnetic metal (TI/MM) interfaces is of great importance for understanding of exotic spin-dependent phenomena and realization of advanced spin-orbitronic devices. Here, we employ a model system of submonolayer transition metal (TM) deposited on the surface of a topological crystalline insulator (TCI) of Pb$_{1-x}$Sn$_{x}$Se to systematically map out the modification of the surface electronic structure by angle-resolved photoemission spectroscopy (ARPES) as a function of coverage. For the polar (111) Pb$_{1-x}$Sn$_{x}$Se surface, we observe the coexistence of the Dirac topological surface states (TSS) and Rashba-split surface states (RSS) induced by the combined effects of inversion-symmetry breaking, surface band bending and orbital angular momentum effects. In particular, we demonstrate very large Rashba splittings can be obtained and the Rashba parameter ($α_R$) can be tuned over a remarkably wide range from 0 to 3.5 eV ${\cdot}$ $\mathring{\mathrm{A}}$, depending on the type and coverage of the TM adatoms. Model-Hamiltonian calculations corroborate the experimental findings and reveal that this coexistence results from the filling of the TSS by the surface doping caused by the TM. In contrast, for the nonpolar (001) surface exhibiting a double Dirac cone topological surface state, the inversion symmetry is preserved and hence no Rashba-split surface states emerge. Instead, surface charge imbalance induces dephasing of the wave functions of the double Dirac cones that diminishes the momentum-space separation between them. These findings shed light on novel phenomena occurring at the topological insulator / transition metal interface, offering a versatile platform for future spintronic and quantum devices.
