  Using fully self consistent methods, we study spin transport in realistic,
fabricable experimental spin valve systems consisting of two magnetic layers, a
superconducting layer, and a spacer normal layer between the ferromagnets. Our
methods ensure that the proper relations between spin current gradients and
spin transfer torques are satisfied. We present results as a function of
geometrical parameters, interfacial barrier values, misalignment angle between
the ferromagnets, and bias voltage. Our main results are for the spin current
and spin accumulation as functions of position within the spin valve structure.
We see precession of the spin current about the exchange fields within the
ferromagnets, and penetration of the spin current into the superconductor for
biases greater than the critical bias, defined in the text. The spin
accumulation exhibits oscillating behavior in the normal metal, with a strong
dependence on the physical parameters both as to the structure and formation of
the peaks. We also study the bias dependence of the spatially averaged spin
transfer torque and spin accumulation. We examine the critical bias effect of
these quantities, and their dependence on the physical parameters. Our results
are predictive of the outcome of future experiments, as they take into account
imperfect interfaces and a realistic geometry.
