  We study the transport properties of nanoscale superconducting (S) devices in
which two superconducting electrodes are bridged by two parallel ferromagnetic
(F) wires, forming an SFFS junction with a separation between the two wires
less than the superconducting coherence length. This allows crossed Andreev
reflection to take place. We find that the resistance as a function of
temperature exhibits behavior reminiscent of the re-entrant effect and, at low
temperatures and excitation energies below the superconducting gap, the
resistance corresponding to antiparallel alignment of the magnetization of the
ferromagnetic wires is higher than that of parallel alignment, in contrast to
the behavior expected from crossed Andreev reflection. We present a model based
on spin-dependent interface scattering that explains this surprising result and
demonstrates the sensitivity of the junction transport properties to
interfacial parameters.
