Magnetic scattering close to a ferromagnet interface: a new type of magnetic proximity effect

The “classical” proximity effect at a ferromagnet–normal metal interface corresponds to the induction of a spin polarization in the normal metal over a length of order of the Fermi wave length. We present here another phenomenon that we also call “magnetic proximity effect”. We consider a diffusive wire of length L, doped with magnetic impurities, and connected to two ferromagnets with an antiparallel magnetization. We show that the semi classical conductance of such a contact increases with the length of the diffusive wire below the spin-flip length. This is reminiscent of the superconducting proximity effect where a similar scaling of the conductance is present. We also consider a diffusive wire with spin-flip scattering connected to a normal metal and a ferromagnet. In this case, only with low transparency contacts does the conductance increase with L. We solve a single impurity “spin-flip Fabry Perot interferometer” for quantum coherent multiple scattering, in which the magnetic proximity effect appears as a resonance in the conductance. U.P.R. 5001 du CNRS, Laboratoire conventionné avec l’Université Joseph Fourier U.M.R. CNRS 5672