Eddy current interactions in a ferromagnet-normal metal bilayer structure, and its impact on ferromagnetic resonance lineshapes

We investigate the effect of eddy currents on ferromagnetic resonance (FMR) in ferromagnet-normal metal (FM/NM) bilayer structures. Eddy-current effects are usually neglected for NM layer thicknesses below the microwave (MW) skin depth (≃800 nm for Au at 10 GHz). However, we show that in much thinne...

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Bibliographic Details
Published in:Journal of applied physics 2015-04, Vol.117 (14)
Main Authors: Flovik, Vegard, Macià, Ferran, Kent, Andrew D., Wahlström, Erik
Format: Article
Language:English
Subjects:
Applied physics
Asymmetry
Copper
Eddy current testing
Eddy currents
Ferromagnetic resonance
Ferromagnetism
Gold
Thickness
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Summary:We investigate the effect of eddy currents on ferromagnetic resonance (FMR) in ferromagnet-normal metal (FM/NM) bilayer structures. Eddy-current effects are usually neglected for NM layer thicknesses below the microwave (MW) skin depth (≃800 nm for Au at 10 GHz). However, we show that in much thinner NM layers (10–100 nm of Au or Cu) they induce a phase shift in the FMR excitation when the MW driving field has a component perpendicular to the sample plane. This results in a strong asymmetry of the measured absorption lines. In contrast to typical eddy-current effects, the asymmetry is larger for thinner NM layers and is tunable through changing the sample geometry and the NM layer thickness.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4917285