Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 28: Surface Magnetism

MA 28.1: Vortrag

Donnerstag, 29. März 2007, 15:15–15:30, H23

Magnetic Exchange Force Microscopy — •Uwe Kaiser, Alexander Schwarz, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg

Magnetic Exchange Force Microscopy (MExFM) is a new technique that was proposed to perform magnetic imaging of insulating or conducting surfaces with atomic resolution. It is based on conventional atomic force microscopy, but uses a magnetic tip, which is approached very closely to a magnetic sample in order to detect the magnetic exchange interaction. To prove the magnetic exchange interaction between the magnetic moments of tip and sample, surfaces with an antiferromagnetic arrangement of spins have been proposed as test systems.

Theoretical calculations indicate the feasibility of MExFM and several attempts have been made to perform such an experiment, however, no clear evidence for successful MExFM imaging has been reported so far.

We succeeded performing MExFM on the antiferromagnetic insulator NiO(001), using the dynamic mode with frequency modulation in the non-contact regime. The images show surface atoms with an additional atomic scale modulation originating from the row-wise antiferromagnetic arrangement of the Ni spins. We discuss experimental prerequisites to perform MExFM and present different tests to unambiguously assign the additional modulation to the magnetic exchange force.