Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 50: [MA] Joint Session "Surface Magnetism I" (jointly with O)

O 50.3: Talk

Wednesday, March 28, 2012, 16:30–16:45, BH 243

First-principles study of the magnetic exchange interaction across a vacuum gap — •Cesar Lazo and Stefan Heinze — Institute of Theoretical Physics and Astrophysics, University of Kiel, Germany

The miniaturization of spintronic devices towards the limit of single atoms calls for a quantification and understanding of the magnetic exchange interaction in atomic-scale junctions. Such a situation can be realized experimentally using a magnetic tip in an atomic force or scanning tunneling microscope. Here, we apply density functional theory to study the exchange interaction between tip and sample, i.e. across a vacuum gap. In particular, we choose the antiferromagnetic monolayer of Fe on W(001) as the sample system and consider different tips composed of Cr, Fe, and Cr/Fe alloys. We calculate the magnetic exchange energies and forces as a function of tip-sample distance. Our calculations are in good agreement with experiments [1]. We analyze the electronic structure of the tip and sample system and explain the origin and nature of the magnetic exchange interaction in this system [2].

• [1] R. Schmidt, C. Lazo, U. Kaiser, A. Schwarz, S. Heinze, and R. Wiesendanger, Phys. Rev. Lett. 106, 257202 (2011).
• [2] C. Lazo and S. Heinze, Phys. Rev. B 84, 144428 (2011).