Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.46: Poster

Tuesday, March 15, 2011, 18:30–22:00, P4

Structural Phases and Magnetism of the Co Monolayer on W(001) — •Arne Köhler, René Schmidt, Alexander Schwarz, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstraße 11, 20355 Hamburg

Theory predicts an antiferromagnetic ground state for a monolayer (ML) of Fe or Co grown pseudomorphically on W(001) [1]. Spin-polarized scanning tunnneling microscopy (SP-STM) could detect the characteristic c(2×2) checkerboard pattern for the Fe ML [2], but not for the Co ML. An alternative approach to map spin-structures with atomic resolution is magnetic exchange force microscopy (MExFM) [3], a novel atomic force microscopy (AFM) based technique, which has been successfully applied to the Fe ML on W(001) [4].

With STM we could detect three phases in the Co ML: a pseudomorphic p(1×1) phase, a reconstructed (2×1) phase and a third unidentified phase. Temperature dependent measurements indicate that the (2×1) phase is more densely packed than the p(1×1) phase. Employing AFM the p(1×1) phase could be also imaged with atomic resolution. Moreover, AFM data revealed the arrangement of atoms within the (2×1) phase, because the positions of atoms are not masked by peculiarities in the local density of states like with STM. First MExFM experiments have been performed as well.

[1] P. Ferriani et al., PRB 71, 024452 (2005).

[2] A. Kubetzka et al., PRL 94, 087204 (2005).

[3] U. Kaiser et al., Nature 446, 522 (2007).

[4] R. Schmidt et al., Nano Lett. 9, 200 (2009).