Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 88: Electronic Structure: Surface Magnetism and Spin Phenomena

O 88.11: Vortrag

Donnerstag, 19. März 2015, 17:30–17:45, MA 042

Exploring the spectroscopic contrast in spin-polarized scanning tunneling microscopy of the antiferromagnetic e-fct Mn surface: From sub-micrometer to Ångstrom length scales — •Jiaming Song, Chii-Bin Wu, Bin Zhang, and Wolfgang Kuch — Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany

We have investigated the antiferromagnetic (AFM) spin structure in AFM/ferromagnetic (FM) exchange-coupled systems in the model system expanded face-centered tetragonal (e-fct) Mn/Co(001) by spin-polarized scanning tunneling microscopy with an in-plane-sensitive Fe ring probe at room temperature. A thickness-dependent study on the surface of Mn films demonstrates that in differential conductance maps on the length scale of 100 nm, Mn exhibits a thickness-dependent layer-wise contrast at +0.2 V sample bias that proves to be mainly of electronic origin and not related to the spin structure. Still, a smaller layer-wise magnetic contribution could coexist. Atomic-scale measurements reveal a non-collinear spin texture of Mn with a (12x2) periodicity and a geometric superstructure with the same unit cell. This spin structure comprises two orthogonal domains, which are ordered on a larger length scale on 6 ML Mn compared to 5 ML. The non-collinear spin texture of Mn could be caused by competing AFM exchange interactions in the reconstructed Mn layer, possibly in combination with the Dzyaloshinsky-Moriya interaction.