Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 26: Surface Magnetism
O 26.6: Vortrag
Dienstag, 6. September 2022, 11:45–12:00, H4
Tuning the electron spin-polarization via tunneling through image states — Maciej Bazarnik1,2 and •Anika Schlenhoff2 — 1Institute of Physics, Poznan University of Technology, Poland — 2Department of Physics, University of Hamburg, Germany
Image-potential states (IS) are unoccupied electronic states in front of polarizable surfaces. Towards step edges, IS energy bands bend [1], leading to laterally localized IS at the rim of nanoislands [2]. Our spin-resolved scanning tunneling microscopy (SP-STM) and spectroscopy experiments on nanomagnets reveal a spin-polarization of the IS rim state, causing a spatial modulation of the electron spin-polarization above uniformly magnetized nanoislands.
An inversion of the electron spin-polarization is found at specific energies. When the electrons relax from the IS into the surface, a spin-transfer torque (STT) is excerted on the sample [3]. We show that according to the IS-induced inversion of the electron spin-polarization, the STT also changes its sign. Our findings indicate that the IS in front of the surface serves as a spin-filter that can tailor the spin-polarization of the resonant tunneling current.
The existence of the rim state and its impact on the electron spin-polarization is expected at the step edge of any magnetic adlayer-substrate system.
Hence, nanostructuring a magnetic surface enables tuning the local spin-polarization and thus tailoring the STT for current-induced magnetization switching.
[1] J.-F. Ge et al., Phys. Rev. B 101, 035152 (2020)
[2] S. Stepanow et al., Phys. Rev. B 83, 115101 (2011).
[3] A. Schlenhoff et al., Phys. Rev. Lett. 109, 097602 (2012).