Varotto Sara, Johansson Annika, Göbel Börge, Vicente-Arche Luis M, Mallik Srijani, Bréhin Julien, Salazar Raphaël, Bertran François, Fèvre Patrick Le, Bergeal Nicolas, Rault Julien, Mertig Ingrid, Bibes Manuel
Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France.
Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany.
Nat Commun. 2022 Oct 18;13(1):6165. doi: 10.1038/s41467-022-33621-1.
Rashba interfaces have emerged as promising platforms for spin-charge interconversion through the direct and inverse Edelstein effects. Notably, oxide-based two-dimensional electron gases display a large and gate-tunable conversion efficiency, as determined by transport measurements. However, a direct visualization of the Rashba-split bands in oxide two-dimensional electron gases is lacking, which hampers an advanced understanding of their rich spin-orbit physics. Here, we investigate KTaO two-dimensional electron gases and evidence their Rashba-split bands using angle resolved photoemission spectroscopy. Fitting the bands with a tight-binding Hamiltonian, we extract the effective Rashba coefficient and bring insight into the complex multiorbital nature of the band structure. Our calculations reveal unconventional spin and orbital textures, showing compensation effects from quasi-degenerate band pairs which strongly depend on in-plane anisotropy. We compute the band-resolved spin and orbital Edelstein effects, and predict interconversion efficiencies exceeding those of other oxide two-dimensional electron gases. Finally, we suggest design rules for Rashba systems to optimize spin-charge interconversion performance.
通过直接和逆埃德尔斯坦效应， Rashba 界面已成为自旋 - 电荷相互转换的有前景的平台。值得注意的是，基于氧化物的二维电子气表现出大且可通过栅极调节的转换效率，这是通过输运测量确定的。然而，缺乏对氧化物二维电子气中 Rashba 分裂能带的直接可视化，这阻碍了对其丰富的自旋轨道物理的深入理解。在这里，我们研究了 KTaO 二维电子气，并使用角分辨光电子能谱证明了它们的 Rashba 分裂能带。用紧束缚哈密顿量对能带进行拟合，我们提取了有效的 Rashba 系数，并深入了解了能带结构复杂的多轨道性质。我们的计算揭示了非常规的自旋和轨道纹理，显示了来自准简并能带对的补偿效应，这强烈依赖于面内各向异性。我们计算了能带分辨的自旋和轨道埃德尔斯坦效应，并预测了超过其他氧化物二维电子气的相互转换效率。最后，我们提出了 Rashba 系统的设计规则，以优化自旋 - 电荷相互转换性能。
