What is the value of the superconducting gap of a F/S/F trilayer?

¹ Centre de Recherches sur les Très Basses Températures (CRTBT (UPR 5001 du CNRS, Laboratoire conventionné avec l'Université Joseph Fourier.) ), CNRS BP 166, 38042 Grenoble Cedex 9, France
² Laboratoire d'Etude des Propriétés Electroniques des Solides (LEPES (UPR 0011 du CNRS, Laboratoire conventionné avec l'Université Joseph Fourier.) ), CNRS BP 166, 38042 Grenoble Cedex 9, France

Corresponding author: melin@grenoble.cnrs.fr

Received: 4 August 2003
Accepted: 24 October 2003

Abstract

Based on the model of F/S/F trilayer with atomic thickness (see Buzdin A. and Daumens M., cond-mat/0305320, Europhys. Lett., 64 (2003) 510) we discuss the relative roles of pair-breaking and proximity effects, as a function of the exchange field, of disorder and of a finite thickness in the superconducting layer. The exchange field can be small (weak ferromagnets) or large (strong ferromagnets) compared to the superconducting gap. With weak ferromagnets we show the existence of a re-entrant superconducting gap for the F/S/F trilayer with atomic thickness in the parallel alignment (equivalent to the F/S bilayer). Qualitatively small disorder is equivalent to reducing the value of the hopping parameters. In the presence of a finite thickness in the superconducting layer, the superconducting gap in the antiparallel alignment is larger than in the parallel alignment, meaning that pair breaking dominates over the proximity effect.