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arXiv · 2207.08698

Direct visualization of Rashba-split bands and spin/orbital-charge interconversion at KTaO$_3$ interfaces

Sara Varotto·Annika Johansson·Börge Göbel·Luis M. Vicente-Arche·Srijani Mallik·Julien Bréhin·Raphaël Salazar·François Bertran·Patrick Le Fèvre·Nicolas Bergeal·Julien Rault·Ingrid Mertig·Manuel Bibes
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Abstract

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 (2DEGs) display a large and gate-tunable conversion efficiency, as determined by transport measurements. However, a direct visualization of the Rashba-split bands in oxide 2DEGs is lacking, which hampers an advanced understanding of their rich spin-orbit physics. Here, we investigate KTaO$_3$-2DEGs 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 2DEGs. Finally, we suggest design rules for Rashba systems to optimize spin-charge interconversion performance.

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Sara Varotto, Annika Johansson, Börge Göbel, Luis M. Vicente-Arche, Srijani Mallik, Julien Bréhin, Raphaël Salazar, François Bertran, Patrick Le Fèvre, Nicolas Bergeal, Julien Rault, Ingrid Mertig, Manuel Bibes. 2022-07-18. Direct visualization of Rashba-split bands and spin/orbital-charge interconversion at KTaO$_3$ interfaces. https://doi.org/10.1038/s41467-022-33621-1

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