The magnetization reversal behavior in Co/Pt multilayers with perpendicular anisotropy are studied by the first order reversal curve (FORC) method. In addition to the previously observed three stage reversal process where domains first nucleate, then expand by domain wall motion and finally annihilate. It is observed that for samples with between 10 and 50 bilayer repeats the magnetization decreases more significantly when the applied field is reversed prior to saturation. This results in FORCs protruding outside of the major loop. X-ray microscopy show a disconnected domain topography when the field is reversed prior to saturation. This is in contrast to an interconnected domain topography when field reversal occurs after first saturating the samples in a large enough field. The disconnected domain topography causes random dipole fields that frustrate the domain growth and prevents domains from growing as closely together as the interconnected structure. This leads to a large enough decrease in the magnetization so as to cause the corresponding FORCs to cross outside of the major loop.
Citation: Applied Physics Letters
Pub Type: Journals
Co/Pt multilayers, FORC, frustration, transmission x-ray microscopy