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 1.2: Hauptvortrag

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

Orbitronics: new torques and magnetoresistance effects — •Mathias Kläui — Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany

Experimentally, orbital currents for efficient manipulation of magnetization have only recently started to be explored. We studied spin orbit torques generated in TmIG/Pt/(Cu(O)x) heterostructures. Varying the CuOx and Pt layer thicknesses, we realized a 16x increase of the spin orbit torques exerted on the TmIG compared to conventional TmIG/Pt [1]. Such an enhancement is extremely surprising if one considers only conventional spin-charge interconversion based on spin orbit coupling effects and given the low spin-orbitcoupling of Cu and Cu(O)x one does not expect large torques. However, the results can be naturally explained as Cu(O)x can generate large orbital currents that are then converted to spin currents in the Pt layer, which then manipulate the TmIG extremely efficiently. In addition, we found in Py/Cu(O)x a Orbital Rashba-Edelstein Magnetoresistance effect related to the conventional spin Hall magnetoresistance [2]. In particular in this work, the length scale of the orbital to spincurrent conversion in Py could be identified as a key step to harnessing orbital currents efficiently even without a heavy metal-based orbital to spin conversion layer [3]. [1] S. Ding, MK et al., Phys. Rev. Lett. 125, 177201 (2020) [2] S. Ding, MK et al., Phys. Rev. Lett. 128, 067201 (2022) [3] D. Go, MK et al., Perspectives Review in EPL 135, 37001 (2021)