Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 50: [MA] Joint Session "Surface Magnetism I" (jointly with O)
O 50.7: Talk
Wednesday, March 28, 2012, 17:45–18:00, BH 243
Tunneling anisotropic magnetoresistance on the atomic scale — •Kirsten von Bergmann1, Matthias Menzel1, David Serrate1, Yasuo Yoshida1, André Kubetzka1, Roland Wiesendanger1, and Stefan Heinze2 — 1Institute of Applied Physics, University of Hamburg, Germany — 2Institute of Theoretical Physics and Astrophysics, University of Kiel, Germany
In non-collinear magnetic structures such as spin spirals, which have recently been found to occur at surfaces due to the Dzyaloshinskii-Moriya interaction [1,2], the spin quantization axis changes from atom to atom. In such a magnetic state the electronic structure of adjacent atoms is not equivalent due to spin-orbit coupling. We demonstrate that this effect leads to a tunneling anisotropic magnetoresistance on the atomic scale which can be detected using scanning tunneling microscopy (STM). This allows to image non-collinear magnetic structures at surfaces by STM with non-magnetic tips. We apply a simple model to relate the changes of the local density of states at the atoms with the tunnel current [3]. Thereby, we can explain the experimentally observed STM and spin-polarized STM images for spin-spirals observed for Mn/W [1,2] and for the atomic-scale magnetic skyrmion lattice found for Fe/Ir(111) [4].
[1] M. Bode et al., Nature 447, 190 (2007).
[2] P. Ferriani et al., Phys. Rev. Lett. 101, 27201 (2008).
[3] S. Heinze, Appl. Phys. A 85, 407 (2006).
[4] S. Heinze et al., Nature Phys. 7, 713 (2011).