Abstract
We report a systematic study of Nb/ferromagnet (FM)/Nb trilayer structures in which the FM layer is one of the strong ferromagnets Co, Fe, Ni, and ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}(\mathrm{Py})$. Accurate control of the FM layer thickness has enabled detailed studies of the magnetic and transport properties in the superconducting state. In all cases, we estimate the thickness of the magnetic dead layer and the exchange energies of the ferromagnetic layers; in doing so, we demonstrate inconsistencies between the exchange energies derived elsewhere from superconductor (S)/FM bilayer experiments and from S/FM/S junction measurements compared to their bulk Curie temperatures, which may hint at further complexity in the underlying physics. We show results in support of a recent publication [J. W. A Robinson et al., Phys. Rev. Lett. 97, 177003 (2006)], focus in detail on a single $0\text{\ensuremath{-}}\ensuremath{\pi}$ phase transition, and show evidence for the appearance of a second harmonic in the current-phase relation at the minimum of the critical current.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
