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MA: Fachverband Magnetismus

MA 25: Surface Magnetism / Magnetic Imaging I

MA 25.1: Talk

Thursday, March 25, 2010, 10:15–10:30, H23

Measuring the distance dependence of the magnetic exchange interaction across a vacuum gap: First experimental results obtained with magnetic exchange force spectroscopy — Rene Schmidt, Uwe Kaiser, •Alexander Schwarz, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany

Magnetic exchange force microscopy (MExFM) has been established as an atomic force microscopy (AFM) based imaging technique to map the spin structures of insulating [1] as well as metallic surfaces [2]. Here we employ the spectroscopic mode, i.e., magnetic exchange force spectroscopy (MExFS), to probe the distance dependence of the magnetic exchange interaction between an atomically sharp magnetic tip and the antiferromagnetically ordered Fe monolayer on W(001). The site specific distance dependence of the total tip-sample interaction is recorded above Fe atoms which exhibit parallel as well as antiparallel atomic magnetic moments with respect to the tip. The contribution of the magnetic exchange interaction can be extracted by subtracting the two curves from each other, because all other interactions are identical on both sites. The experimental results are compared with theoretical calculations [3] and thereby allow us to determine the distance dependence of the effective coupling constant J between the tip apex atoms and the surface atoms underneath.

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

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

[3] C. Lazo et al., Phys. Rev. B 78, 214416 (2008).