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Scanning Force Microscopy – Applications in Magnetism and Surface Science
|Hans J. Hug 1,2, Iris Schmid 1, Peter Kappenberger 1, Sara Romer 1, Tim Ashworth 2, Magdalena Parlinska-Wojtan 1, Quang Thai 1, Sasa Vranjkovic 1, Raphaelle Dianoux 1, Shigeki Kawai 1|
1. Empa, Laboratory for Nanoscale Materials Science, Ueberlandstrasse 129, Dübendorf 8600, Switzerland
Since its invention in 1986 the AFM has evolved into an instrument that is able to map various physical or chemical properties on a local scale with up to atomic resolution. The measured tip-sample interaction is due to long and short range forces. Among these are electrostatic, magnetic, van der Waals forces and short-range forces due to incipient chemical bonds between the tip apex and the sample atoms, respectively.
In a first part, I will first concentrate on the mapping of magnetic structures with high sensitivity and spatial resolution. Using ultra-high aspect ratio silicon tips coated with ultrathin ferromagnetic layers, magnetic stray fields can be routinely imaged with 10nm spatial resolution, and sub-monolayer sensitivity. The latter turned out to be particularly useful to map the spatial distribution of uncompensated spins at the interface between ferromagnetic and antiferromagnetic thin films. Based on this infomration an improved understanding of the exchange bias effect was ontained and materials with higher exchange anisotropy energies could be designed and fabricated.
In a second part, atomic resolution imaging will be addressed. Since the first demonstration in 1995 atomic resolution images were obtained on a large variety of surfaces. Site-specific measurements of the tip-sample interaction forces performed at cryogenic temperatures have provided relevant information on the nature of the incipient chemical bond between the tip apex and selected surfaces sites and on the imaging mechanisms. However, the routine use of AFM in surface science has still remained much more challenging than in the case of STM. This is presumably due to the presently used operation modes. Approaches to overcome the present limitations in AFM will be discussed.
Presentation: Invited at E-MRS Fall Meeting 2007, Symposium J, by Hans J. Hug
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-31 14:25 Revised: 2009-06-07 00:44