Spin-valve magnetic sandwich in a Josephson junctionA. Vedyayev1, C. Lacroix2, N. Pugach1 and N. Ryzhanova1
1 Faculty of Physics, M. V. Lomonosov Moscow State University Moscow 119992, Russia
2 Laboratoire Louis Néel, CNRS - BP 166, 38042 Grenoble Cedex 9, France
received 22 March 2005; accepted in final form 17 June 2005
published online 14 July 2005
The Josephson current is calculated in a SFNFS junction, which consists of two ferromagnetic layers (F) separated by a thin non-magnetic spacer (N) and connected to superconducting electrodes (S). Gorkov equations are solved taking into account the fact that s-d scattering is the main scattering mechanism in the 3d ferromagnetic metals and it effectively destroys BCS correlation. It allows us to consider both strong and weak exchange field I: or ( is the relaxation time in F-layers). It is shown that the critical current J oscillates as a function of F-layers thickness and the oscillation period depends only on I. The s-d scattering effectively acts as an additional to the exchange magnetic-field mechanism for the suppression of BCS correlation in the ferromagnet. The s-d scattering is shown to be the reason of suppression of the Josephson current enhancement in the antiparallel configuration.
74.50.+r - Tunneling phenomena; point contacts, weak links, Josephson effects.
72.25.-b - Spin polarized transport.
73.63.-b - Electronic transport in nanoscale materials and structures.
© EDP Sciences 2005