发表机构
RWTH Aachen University（亚琛工业大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究建立硅中自旋-谷耦合的对称性理论，揭示不依赖界面的本征Dresselhaus自旋-轨道耦合，推导相关耦合机制并预测鲁棒的谷分裂，为硅量子器件操控自旋与谷自由度提供新途径。
AI 中文摘要
我们建立了硅中自旋-轨道-谷耦合的对称性理论，揭示了一种不依赖于界面或外电场的本征Dresselhaus自旋-轨道耦合来源。将谷自由度视为带有对称性的量子自由度，我们证明Dresselhaus相互作用必然是谷非对角的，且与谷泡利矩阵τ₁成正比的体贡献在对称性上是允许的。紧束缚计算得到的体耦合比典型的界面诱导自旋-轨道耦合大一个数量级以上；通过界面诱导机制达到相同能量尺度所需的电场约为典型电场的50倍。我们进一步推导了由磁场梯度产生的对称性允许的自旋-谷耦合，并展示了它们如何解释微磁体实验中观测到的谷依赖塞曼分裂。背景磁场偏离平面的微小倾斜会产生与B_z线性相关的额外各向同性贡献，为相应耦合常数提供了实验可观测的特征。最后，我们预测了τ₃通道中与自旋无关的微磁体诱导谷分裂，其与合金无序产生的τ₁,₂通道不同，因此对无序诱导的抵消具有鲁棒性。这些结果确立了谷对称性是硅自旋-轨道物理的基本要素，并为硅量子器件中自旋和谷自由度的控制与探测提供了新机制。
英文摘要
We develop a symmetry-based theory of spin-orbit-valley coupling in silicon that reveals an intrinsic source of Dresselhaus spin-orbit coupling independent of interfaces or external electric fields. Treating the valley degree of freedom as a symmetry-carrying quantum degree of freedom, we show that the Dresselhaus interaction is necessarily valley off-diagonal and that a bulk contribution proportional to the valley Pauli matrix $τ_1$ is symmetry allowed. Tight-binding calculations yield a bulk coupling more than an order of magnitude larger than typical interface-induced spin-orbit coupling; achieving the same energy scale through the interface-induced mechanism would require electric fields roughly 50 times larger than typical fields. We further derive the symmetry-allowed spin-valley couplings generated by magnetic-field gradients and show how they account for the valley-dependent Zeeman splitting observed in micromagnet experiments. A slight tilt of the background magnetic field out of the plane produces an additional isotropic contribution linear in $B_z$, providing an experimentally accessible signature of the corresponding coupling constant. Finally, we predict a spin-independent micromagnet-induced valley splitting in the $τ_3$ channel, which is distinct from the $τ_{1,2}$ channels generated by alloy disorder and therefore remains robust against disorder-induced cancellation. These results establish valley symmetry as a fundamental ingredient in the spin-orbit physics of silicon and provide new mechanisms for controlling and probing spin and valley degrees of freedom in silicon quantum devices.
