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(a) Scanning electron microscope image of the permalloy nanowire. (b) Micromagnetic simulation of the relaxed magnetic vortex domain wall pinned at the wire constriction. (c) STXM image of the nanowire under investigation showing XMCD contrast. (d) Calculated current distribution in the wire, showing a homogeneous current flow in the region of vortex gyration. (e) Schematic illustration of the experimental geometry; the wire itself is tilted by −10° with respect to the horizontal axis.
Experimental data of the relative phase of the vortex core gyration due to ac current injection with a constant phase . The fitted phase response corresponds to a resonance frequency , indicated by the blue vertical bar. The corresponding gyration trajectory for an excitation frequency of 340 MHz, close to the resonance frequency (see red datapoint), is shown in Fig. 3.
(a) The experimentally determined vortex core trajectory at near the resonance frequency . The ellipse is fitted through the data points and its eccentricity is a measure of the local pinning potential well. (b) Differential STXM snapshots indicate elliptical gyration of the vortex core under continuous ac excitation with 340 MHz. To remove nonmagnetic contrast, two images with out-of-plane XMCD contrast recorded at 180° phase difference are divided by each other.
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