Showing papers by "Christoph Quitmann published in 2013"

The Materials Science beamline upgrade at the Swiss Light Source

Abstract: The Materials Science beamline at the Swiss Light Source has been operational since 2001 In late 2010, the original wiggler source was replaced with a novel insertion device, which allows unprecedented access to high photon energies from an undulator installed in a medium-energy storage ring In order to best exploit the increased brilliance of this new source, the entire front-end and optics had to be redesigned In this work, the upgrade of the beamline is described in detail The tone is didactic, from which it is hoped the reader can adapt the concepts and ideas to his or her needs

Topology and origin of effective spin meron pairs in ferromagnetic multilayer elements.

Abstract: We report on pairs of converging-diverging spin vortices in $\mathrm{Co}/\mathrm{Rh}/\mathrm{NiFe}$ trilayer disks. The lateral magnetization distribution of these effective spin merons is directly imaged by means of element-selective x-ray microscopy. By this method, both the divergence and circulation states of the individual layers are identified to be antisymmetric. Reversal measurements on corresponding continuous films reveal that biquadratic interlayer exchange coupling is the cause for the effective meron pair formation. Moreover, their three-dimensional magnetization structure is determined by micromagnetic simulations. Interestingly, the magnetic induction aligns along a flux-closing torus. This toroidal topology enforces a symmetry break, which links the core polarities to the divergence configuration.

Dynamic stabilization of nonequilibrium domain configurations in magnetic squares with high amplitude excitations

Abstract: We explore the linear and nonlinear dynamic regimes of micrometer-scale soft magnetic squares with an in-plane uniaxial anisotropy, recording the response of the magnetization in the spatial domain under a continuous sinusoidal excitation with time-resolved scanning transmission x-ray microscopy. Increasing the excitation field amplitude leads to the dynamic stabilization of nonequilibrium domain configurations, which appear at threshold amplitudes and return to the equilibrium configuration when the amplitude is reduced. On imaging the magnetization in the transition region between two stable magnetic configurations, we observe small domains originating from the vortex core. Dynamic micromagnetic simulations of the domain configuration provide qualitative agreement with the experimental data and insight into the energy dissipation and spin wave contributions.