Regensburg 2022 – wissenschaftliches Programm

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SYOP: Frontiers of Orbital Physics: Statics, Dynamics, and Transport of Orbital Angular Momentum

SYOP 1: Frontiers of Orbital Physics: Statics, Dynamics, and Transport of Orbital Angular Momentum

SYOP 1.3: Hauptvortrag

Montag, 5. September 2022, 10:30–11:00, H1

Spin-orbitronics in two dimensional systems: Orbital magnetization and Edelstein effect — •Börge Göbel — Martin-Luther-Universität Halle-Wittenberg

The total angular momentum is the sum of the orbital and spin angular momenta. However, in equilibrium, the orbital contribution to the magnetization is often quenched by the crystal field which is why it is typically significantly smaller than the spin contribution. In this talk, I will present the generation of a significant orbital magnetization.

In non-collinear spin textures crystal symmetries are broken and the quenching is lifted. In topologically non-trivial skyrmion crystals, for example, the emergent field forces electrons on orbital trajectories, like in the quantum Hall effect, which leads to the generation of a considerable orbital magnetization with de Haas-Van Alphen oscillations [1].

In two-dimensional electron gases (2deg), e.g. at the interface of STO/AlO [2,3] or KTO/AlO [4], the inversion symmetry is broken so that an (inverse) Edelstein effect arises. The application of a charge current leads to the generation of spin and orbital magnetization densities and vice versa. While the measured spin-charge conversion efficiency is already enormous [2], the orbital conversion efficiency is predicted to be even an order of magnitude larger [3], especially in the KTO-based 2deg where we observe a significant Rashba splitting [4].

[1] BG et al. PRB 99, 060406 (2019)

[2] Vaz, BG et al. Nature Materials 18, 1187 (2019)

[3] Johansson, BG et al. PRResearch 3, 013275 (2021)

[4] Varotto, BG et al. arxiv: 2207.08698 (2022)