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O: Fachverband Oberflächenphysik

O 51: Surface Magnetism

O 51.1: Talk

Wednesday, March 29, 2023, 11:30–11:45, REC C 213

Turning by hydrogen adsorption an exchange frustrated spin-spiral into elliptical magnetic skyrmions — Timo Knispel¹, Vasily Tseplyaev², Markus Hoffmann², Gustav Bihlmayer², Stefan Blügel², Thomas Michely¹, and •Jeison Fischer¹ — ¹II Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Cologne, Germany — ²Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

Spin-spiral states may emerge either from the frustration of Heisenberg-type exchange interactions or from the competition of exchange and the relativistic Dzyaloshinskii-Moriya interaction resulting in atomic scale and mesoscale textures, respectively. However, to turn frustration-stabilized spin-spirals into skyrmions, high magnetic fields are required, hardly achievable in the lab. We report on a new principle using hydrogen adsorption to unwind an exchange-stabilized spin-spiral into skyrmions at accessible fields. With spin-polarized scanning tunneling microscopy we identify an atomic scale right-handed Néel-type spin spiral on the double layer Fe on Ir(110). Density functional theory calculations confirm the spin spiral is mainly frustration-stabilized with a formation energy of -12 meV/Fe with respect to ferromagnetic state. A field of the order of 80 T would be required to unwind the spin spiral. After adsorption of hydrogen, we observe that the nature of the spin spiral becomes of Dzyaloshinskii-type with a seven times longer period. Elliptical skyrmions can be formed at moderate magnetic fields.