Europhys. Lett.
Volume 71, Number 4, August 2005
Page(s) 679 - 685
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 14 July 2005
Europhys. Lett., 71 (4), pp. 679-685 (2005)
DOI: 10.1209/epl/i2005-10118-y

Spin-valve magnetic sandwich in a Josephson junction

A. 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: $I\tau_f\gg1$ or $I\tau_f\ll 1$ ($\tau_f$ 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.

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