current-phase relation in SFS junctions with decoherence in the ferromagnetR. Mélin
Centre de Recherches sur les Très Basses Températures (CRTBT) Boîte Postale 166, F-38042 Grenoble Cedex 9, France
received 14 June 2004; accepted in final form 26 October 2004
published online 8 December 2004
We propose a theoretical description of the current-phase relation in SFS junctions at the 0- 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- 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 , larger than the elastic scattering length ld 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 in the absence of decoherence). The fit of experiments works well for the amplitude of both the and harmonics.
74.50.+r - Tunneling phenomena; point contacts, weak links, Josephson effects.
74.78.Fk - Multilayers, superlattices, heterostructures.
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