current-phase relation in SFS junctions with decoherence in the ferromagnet

Centre de Recherches sur les Très Basses Températures (CRTBT) Boîte Postale 166, F-38042 Grenoble Cedex 9, France

Corresponding author: regis.melin@grenoble.cnrs.fr

Received: 14 June 2004
Accepted: 26 October 2004

Abstract

We propose a theoretical description of the current-phase relation in SFS junctions at the 0-π crossover obtained in recent experiments by Sellier et al. (Phys. Rev. Lett., 92 (2004) 257005, cond-mat/0406236), where it was suggested that a strong decoherence in the magnetic alloy can explain the magnitude of the residual supercurrent at the 0-π crossover. To describe the interplay between decoherence and elastic scattering in the ferromagnet, we use an analogy with crossed Andreev reflection in the presence of disorder. The supercurrent as a function of the length R of the ferromagnet decays exponentially over a length ξ, larger than the elastic scattering length l_d in the absence of decoherence, and smaller than the coherence length in the absence of elastic scattering on impurities. The best fit leads to , where is the exchange length of the diffusive system without decoherence (also equal to ξ in the absence of decoherence). The fit of experiments works well for the amplitude of both the and harmonics.