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MA: Fachverband Magnetismus

MA 33: Surface Magnetism II (jointly with O)

MA 33.1: Talk

Wednesday, March 9, 2016, 15:00–15:15, H31

Nanoscale and proximity effects on low-dimensional helical magnetic structures — •Jeison A. Fischer, Leonid M. Sandratskii, Soo-hyon Phark, Safia Ouazi, Dirk Sander, and Stuart Parkin — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

The finite size of nanoscale magnetic structures with non-collinear spin order influences strongly their magnetic state. Also, the proximity to a ferromagnetic material affects the nanoscale spin-order [1]. We combine symmetry arguments, first-principles calculations and spin-resolved scanning tunneling spectroscopy at 10 K and in magnetic fields to study an 1D helical magnet of some nm extension in proximity to both ferromagnetic Co and vacuum regions. We report a non-uniform distortion of the spin helix in an Fe bilayer on Cu(111)[1], where the spin orientation deviates from that of an ideal helical structure. The proximity to either Co or vacuum leads to distortions of the spin orientation within nm range of the respective interface. The distortions give rise to specific energy and position dependent modifications of the spin-resolved electronic density of states. These effects have not been discussed before. We demonstrate that, in contrast to an ideal helix of infinite length, the lack of symmetry of the nm-long distorted Fe spin helix, induces an energy dependence in STS of the magnetization of the differential tunneling conductance at tip position.

[1] Phark, S. H.; Fischer, J. A.; Corbetta, M.; Sander, D.; Nakamura, K. & Kirschner, J. Reduced-dimensionality-induced helimagnetism in iron nanoislands Nat. Commun. 5 (2014) 5183.