Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 8: Magnetic Imaging

MA 8.6: Talk

Monday, February 25, 2008, 16:30–16:45, H 1012

Tip Effects in Magnetic Exchange Force Microscopy — •Uwe Kaiser, Alexander Schwarz, and Roland Wiesendanger — Institut für Angewandte Physik, Jungiusstr. 11, 20355 Hamburg

Magnetic Exchange Force Microscopy (MExFM) is a novel technique that was invented in order to perform magnetic imaging of insulating or conducting surfaces with atomic resolution [1]. It is based on conventional atomic force microscopy but uses a magnetic tip, which is approached very closely to a magnetic sample to detect the magnetic exchange interaction between tip and sample.

In our study we analyze the (001) surface of NiO by means of MExFM. The measurements have been carried out in a home-built microscope, operated in UHV at a temperature of 8  K. As magnetic probes we used supersharp silicon cantilevers that were coated with 22 nm of iron as a ferromagnetic layer. To get a favourable alignment between the spins of tip and sample we applied a magnetic field of 5 T perpendicular to the sample surface. Using this set-up we obtained magnetic resolution of the antiferromagnetically arranged nickel atoms on the atomic scale. However, some of our experimental results show sudden changes or even a contrast reversal of the magnetic contrast. These experimental findings are discussed with respect to the influence of the orientation of the spin at the tip apex and the applied magnetic field.

[1] U. Kaiser, A. Schwarz, and R. Wiesendanger, Nature 446, 522 (2007).