轨道杂化在Cu/WO₃界面诱导巨大的立方 Rashba 效应
Orbital Hybridization Induces Giant Cubic Rashba Effect at Cu/WO$_{3}$ Interface
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中文总结 AI 辅助
该研究以 Cu(001)/WO₃(001)为模型，通过第一性原理计算，发现 Cu 与 WO₃ 界面因轨道杂化产生强大 Rashba 自旋分裂，立方 Rashba 贡献随 Cu 厚度变化，可提取巨大本征参数，多种界面结构中效应仍存，确定此界面为探索 Rashba 物理的新平台。
中文摘要 AI 辅助
传统上，利用 Rashba 自旋轨道相互作用及相关自旋电子功能依赖于含元素重金属的金属表面或界面。本文以 Cu(001)/WO₃(001)为模型异质结构，通过第一性原理计算表明，轻金属 Cu 与能带绝缘体 WO₃ 形成的界面态，因线性和立方 Rashba 效应相互作用呈现出强大的 Rashba 自旋分裂。自旋分裂由 W 原子的强自旋轨道耦合驱动，界面处的 W-Cu 轨道杂化促成。立方 Rashba 贡献随 Cu 厚度渐近增长，可由真空/Cu 和 Cu/WO₃ 界面间的交叉耦合解释。在较大 Cu 厚度时交叉耦合减弱，从而能提取出约 -1.93 eV ų 的巨大本征立方 Rashba 参数。线性 Rashba 参数受交叉耦合影响较弱，约在 0.30 至 0.49 eV Å 之间变化。此外，在多种界面几何结构和 Cu 表面取向（包括(110)和(111)）中，可观的线性和立方 Rashba 效应依然存在。本研究将 Cu/WO₃ 界面确定为探索包括线性和非线性自旋轨道现象在内的丰富 Rashba 物理的新型轻金属/重元素基氧化物平台。
英文摘要
Harnessing Rashba spin-orbit interaction and related spintronic functionalities has traditionally relied on metallic surfaces or interfaces containing elemental heavy metals. Here, using first-principles calculations and Cu(001)/WO$_3$(001) as a model heterostructure, we show that interfacing a light metal, Cu, with a band insulator, WO$_3$, yields an interface state that exhibits a robust Rashba spin splitting arising from the interplay between linear and cubic Rashba effects. The spin splitting is driven by the strong spin-orbit coupling of W atoms and enabled by W-Cu orbital hybridization at the interface. The cubic Rashba contribution asymptotically grows with Cu thickness and can be explained in terms of cross-coupling between the vacuum/Cu and Cu/WO$_3$ interfaces. This interfacial cross-coupling, however, diminishes at larger Cu thicknesses, allowing us to extract the intrinsic cubic Rashba parameter, which has a giant value of approximately -1.93 eV $Å^3$. In contrast, the linear Rashba parameter is only weakly affected by this cross-coupling and varies from approximately 0.30 to 0.49 eV Å. We further show that sizable linear and cubic Rashba effects persist across several interface geometries and Cu surface orientations, including (110) and (111). Our work identifies the Cu/WO$_3$ interface as a novel light-metal/heavy-element-based oxide platform for exploring the rich spectrum of Rashba physics, including linear and nonlinear spin-orbit phenomena.
