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Biomedical subjects

P Kappenberger

Publications and source records attributed to P Kappenberger.

3 recordsLinked to original sources
PubMed2003

Direct imaging and determination of the uncompensated spin density in exchange-biased CoO/(CoPt) multilayers.

Magnetic force microscopy (MFM) measurements were performed on an exchange-biased CoO/(CoPt) multilayer sample at 7.5 K. Applying an external magnetic field of up to 7 T saturates the ferromagnetic layer and the remaining uncompensated antiferromagnetic spins at the antiferromagnet-ferromagnet interfaces are imaged with high lateral resolution. The coupling between the uncompensated spins and the spins in the ferromagnet are found to be antiferromagnetic. Quantitative analysis of the MFM images revealed that 7% of the spins at the interface are uncompensated and contribute to the exchange biasing.

Journal Article↗
PubMed2001

Quantitative measurement of short-range chemical bonding forces.

We report direct force measurements of the formation of a chemical bond. The experiments were performed using a low-temperature atomic force microscope, a silicon tip, and a silicon (111) 7x7 surface. The measured site-dependent attractive short-range force, which attains a maximum value of 2.1 nanonewtons, is in good agreement with first-principles calculations of an incipient covalent bond in an analogous model system. The resolution was sufficient to distinguish differences in the interaction potential between inequivalent adatoms, demonstrating the ability of atomic force microscopy to provide quantitative, atomic-scale information on surface chemical reactivity.

Journal Article↗