title: Time-resolved imaging of magnetic vortex dynamics using holography with extended reference autocorrelation by linear differential operator.
abstract: The magnetisation dynamics of the vortex core and Landau pattern of magnetic thin-film elements has been studied using holography with extended reference autocorrelation by linear differential operator (HERALDO). Here we present the first time-resolved x-ray measurements using this technique and investigate the structure and dynamics of the domain walls after excitation with nanosecond pulsed magnetic fields. It is shown that the average magnetisation of the domain walls has a perpendicular component that can change dynamically depending on the parameters of the pulsed excitation. In particular, we demonstrate the formation of wave bullet-like excitations, which are generated in the domain walls and can propagate inside them during the cyclic motion of the vortex core. Based on numerical simulations we also show that, besides the core, there are four singularities formed at the corners of the pattern. The polarisation of these singularities has a direct relation to the vortex core, and can be switched dynamically by the wave bullets excited with a magnetic pulse of specific parameters. The subsequent dynamics of the Landau pattern is dependent on the particular configuration of the polarisations of the core and the singularities.
authors: School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom.
authors: N
authors: N
authors: Bukin
authors: School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom.
authors: C
authors: C
authors: McKeever
authors: School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom.
authors: E
authors: E
authors: Burgos-Parra
authors: School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom.
authors: P S
authors: PS
authors: Keatley
authors: School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom.
authors: R J
authors: RJ
authors: Hicken
authors: School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom.
authors: F Y
authors: FY
authors: Ogrin
authors: CNRS, SIMAP, F-38000 Grenoble, France.
authors: G
authors: G
authors: Beutier
authors: Paul Scherrer Institute, 5232 Villigen, Switzerland.
authors: M
authors: M
authors: Dupraz
authors: SOLEIL Synchrotron, 91192 Saint-Aubin, France.
authors: H
authors: H
authors: Popescu
authors: SOLEIL Synchrotron, 91192 Saint-Aubin, France.
authors: N
authors: N
authors: Jaouen
authors: European Synchrotron Radiation Facility, F-38043 Grenoble Cedex 9, France.
authors: F
authors: F
authors: Yakhou-Harris
authors: Department of Physics, University of York, York, YO10 5DD, United Kingdom.
authors: S A
authors: SA
authors: Cavill
authors: Diamond Light Source, Harwell Science and innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom.
authors: G
authors: G
authors: van der Laan