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O: Fachverband Oberflächenphysik

O 89: Spins on surfaces at the atomic scale II

O 89.7: Vortrag

Donnerstag, 12. März 2026, 16:30–16:45, WILL/A317

Confinement-modulated spin-orbit coupling tuned with atomic-scale gating fields — •Hermann Osterhage, Julian H. Strik, Anna M. H. Krieg, Ivan Ado, Mikhail Titov, Daniel Wegner, and Alexander A. Khajetoorians — Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands

In 2D, inversion symmetry breaking combined with a sizeable potential gradient leads to the well-known Rashba spin-orbit coupling (SOC), locking the spin and momentum. Using potential gradients to induce SOC is not limited to the Rashba case, but may be extended to lower dimensional structures, such as quantum dots. However, tuning SOC in these limits is challenging: it requires potential gradients that are comparable to the size of the confined structure itself.

Here, we demonstrate a new type of SOC, akin to the Rashba effect, where large potential gradients are formed within an atomically patterned quantum dot. Using low-temperature scanning tunnelling microscopy and spectroscopy we create quantum dots of various shapes and sizes by patterning individual Cs ions on the surface of InSb(110). We find that we can tune the confinement potential, as shown by the presence of multiple localized states. In addition, by probing the resultant multiplet structure, we identify zero-field splittings within a given quantum dot that are induced by the geometry of the potential. We also discuss the magnetic field dependence of this level structure and explain the findings based on the 8-band Kane model.
[1] E. Sierda et al, Science 380, 1048 (2023).

Keywords: STM; Quantum dots; Spin-orbit coupling