title: Quantitative measurements of magnetic stray field dynamics of Permalloy particles in a photoemission electron microscopy.
abstract: By example of a Permalloy particle (40 × 40 μm(2) size, 30 nm thickness) we demonstrate a procedure to quantitatively investigate the dynamics of magnetic stray fields during ultrafast magnetization reversal. The measurements have been performed in a time-resolving photoemission electron microscope using the X-ray magnetic circular dichroism. In the particle under investigation, we have observed a flux-closure-dominated magnetic ground structure, minimizing the magnetic stray field outside the sample. A fast magnetic field pulse introduced changes in the micromagnetic structure accompanied with an incomplete flux closure. As a result, stray fields arise along the edges of domains, which cause a change of contrast and an image deformation of the particles geometry (curvature of its edge). The magnetic stray fields are calculated from a deformation of the X-ray magnetic circular dichroism (XMCD) images taken after the magnetic field pulse in a 1 ns interval. These measurements reveal a decrease of magnetic stray fields with time. An estimate of the lower limit of the domain wall velocity yields about 2 × 10(3) m s(-1).
authors.affiliation: Institute of Physics, University of Mainz, Mainz, Germany. nepijko@uni-mainz.de
authors.forename: S A
authors.initials: SA
authors.lastname: Nepijko
authors.forename: A
authors.initials: A
authors.lastname: Krasyuk
authors.forename: A
authors.initials: A
authors.lastname: Oelsner
authors.forename: C M
authors.initials: CM
authors.lastname: Schneider
authors.forename: G
authors.initials: G
authors.lastname: Schönhense