Enhanced Supercurrents in Josephson Junctions Containing Nonparallel Ferromagnetic Domains

Abstract

$\ensuremath{\pi}$ coupling may arise when a ferromagnet forms a link between two superconductors of an artificial Josephson junction. Using a trilayer $\mathrm{Fe}/\mathrm{Cr}/\mathrm{Fe}$ barrier in which the Cr thickness determines the alignment of the Fe layers, we show that the critical currents are substantially enhanced in the antiparallel configuration. The result agrees with existing superconductor-ferromagnet proximity theory according to which the phase-controlling effects of ferromagnets on Cooper pairs can be minimized by arranging their moments in a nonparallel way [Bergeret et al., Phys. Rev. Lett. 86, 3140 (2001); Blanter et al., Phys. Rev. B 69, 024525 (2004)].