Orbital and Spin Edelstein Effects in KTaO₃(110) Two-Dimensional Electron Gases.

Abstract

The orbital Edelstein effect converts an electric field into a non-equilibrium orbital polarization, opening new opportunities for orbitronics. Although signatures of the orbital Edelstein effect have been reported, its microscopic mechanisms and quantitative validation remain underexplored. Here, by directly linking the atomic structure of <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>KTaO</mi> <mn>3</mn></msub> <annotation>${\rm KTaO}_3$</annotation></semantics> </math> (110) two-dimensional electron gases to both their calculated and measured electronic band dispersions, we predict and provide experimental evidence for a significant orbital Edelstein contribution that governs the anisotropy of its harmonic transport response. Scanning transmission electron microscopy and electron energy-loss spectroscopy resolve the interfacial atomic configuration, which is used as input for density-functional calculations. Angle-resolved photoemission spectroscopy then confirms the resulting band structure, which is fitted by a tight-binding model enabling computation of the spin and orbital Edelstein responses. Harmonic magnetotransport measurements reveal an anisotropic response that cannot be accounted for within a purely spin Edelstein framework, and is quantitatively reproduced by including an orbital contribution of order 20%. Our results establish <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>KTaO</mi> <mn>3</mn></msub> <annotation>${\rm KTaO}_3$</annotation></semantics> </math> (110) as a model platform for orbitronics and demonstrate a pathway to generate and harness orbital polarization in quantum oxide systems while also offering new insights into pairing mechanisms in their superconducting state.