Effect of Meissner Screening and Trapped Magnetic Flux on Magnetization Dynamics in Thick Nb/Ni80Fe20/Nb Trilayers

Kun-Rok Jeon, Chiara Ciccarelli, Hidekazu Kurebayashi, Lesley F. Cohen, Xavier Montiel, Matthias Eschrig, Thomas Wagner, Sachio Komori, Anand Srivastava, Jason W. A. Robinson, Mark G. Blamire

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Abstract

We investigate the influence of Meissner screening and trapped magnetic flux on magnetization dynamics for a Ni80Fe20 film sandwiched between two thick Nb layers (100 nm) using broadband (5–20 GHz) ferromagnetic resonance (FMR) spectroscopy. Below the superconducting transition Tc of Nb, significant zero-frequency line broadening (5–6 mT) and dc-resonance field shift (50 mT) to a low field are both observed if the Nb thickness is comparable to the London penetration depth of Nb films (≥100 nm). We attribute the observed peculiar behaviors to the increased incoherent precession near the Ni80Fe20/Nb interfaces and the effectively focused magnetic flux in the middle Ni80Fe20 caused by strong Meissner screening and (defect-)trapped flux of the thick adjacent Nb layers. This explanation is supported by static magnetic properties of the samples and comparison with FMR data on thick Nb/Ni80Fe20 bilayers. Great care should, therefore, be taken in the analysis of FMR response in ferromagnetic Josephson structures with thick superconductors, a fundamental property for high-frequency device applications of spin-polarized supercurrents.
Original languageEnglish
Article number014061
Pages (from-to)1-8
Number of pages8
JournalPhysical Review Applied
Volume11
Issue number1
DOIs
Publication statusPublished - 30 Jan 2019

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