Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 118: Surface Magnetism II (joint session O/MA)
O 118.6: Talk
Friday, March 20, 2020, 11:45–12:00, GER 38
Bloch-type spin helix in bilayer Fe islands on Ir(110) by spin polarized STM — Jeison A. Fischer1, •Timo Knispel1, Mahasweta Bagchi1, Jens Brede1, Vasily Tseplyaev2, Markus Hoffmann2, Stefan Blügel2, and Thomas Michely1 — 1II. Physikalisches Institut, Universität zu Köln, 50937 Cologne, Germany — 2Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
Most work on interfacial chiral spin textures focused on films exhibiting C3v symmetry and isotropic Dzyaloshinskii-Moriya interaction (DMI), known to only support Néel-type spin helices and skyrmions [1]. In contrast, C2v symmetry systems such as the (110) surface of an fcc crystal, are predicted to show anisotropic DMI leading to various scenarios of topological pattern formation [2]. Fully unexpectedly, our spin-polarized STM/STS study reveals a magnetic stripe phase, due to a spin helix with a period of 1.2 nm along the [-1 1 0] direction in bilayer Fe islands on unreconstructed Ir(110). Based on detailed field dependent measurements with a vector magnet, we conclude that the chirality of the spin helix is of Bloch-type, where the rotation is perpendicular with the propagation direction. This contradicts the assumption of the spin helix being induced by an interface in-plane DMI vector. Combined with theoretical insights, we discuss our findings in terms of the formation energy in systems with C2v symmetry. Funding: CRC1238 and the Jülich Supercomputing Center project CJIAS1F
[1] S. Heinze et al. Nat. Phys. Vol.7, p.713 (2011).
[2] M. Hoffmann et al. Nat. Commun. Vol.8, p.308 (2017).