Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 98: Electronic structure: Surface magnetism and spin phenomena I

O 98.12: Talk

Thursday, March 15, 2018, 18:00–18:15, MA 042

Fe/Rh(111): a magnetic ground state driven by higher-order spin interactions — Markus Hoffmann, •Gustav Bihlmayer, and Stefan Blügel — Peter Grünberg Institut (PGI-1) & Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Although for S > 1/2 systems higher order spin interactions can be expected to get important, the magnetism of transition metals is often studied in the (classical) Heisenberg model. Surprisingly, the two-spin interactions from this model describe many systems rather well, only in some cases biquadratic or cyclic four-spin terms have to be added. Here, we present the system of one monolayer Fe on Rh(111) where an even more exotic term, a 3-site 4-spin interaction, is necessary to explain the ground state that was predicted by density functional theory [1] and recently confirmed experimentally [2]. The Fe layer shows a double–row-wise antiferromagnetic structure, that can be described as double-Q state. Another double-Q structure, modulating the spins in the orthogonal direction, would be energetically degenerate in the extended Heisenberg model (including biquadratic and cyclic four-spin terms) but is disfavored by the 3-site 4-spin term. Our calculations suggest that the size of this term can be as large (or even exceed) the well known four-spin interactions and that this finding is not limited to the Fe/Rh system.

[1] A. Al-Zubi et al., phys. stat. sol. (b) 248, 2242 (2011).

[2] A. Krönlein et al., submitted (2017).