Angular dependence of superconductivity in superconductor/spin-valve heterostructures

We report measurements of the superconducting transition temperature, Tc, in CoO/Co/Cu/Co/Nb multilayers as a function of the angle alpha between the magnetic moments of the Co layers. Our measurements reveal that Tc ( alpha ) is a nonmonotonic function, with a minimum near alpha = [pi]/2. Numerical self-consistent solutions of the Bogoliubov-de Gennes equations quantitatively and accurately describe the behavior of Tc as a function of alpha and layer thicknesses in these superconductor/spin-valve heterostructures. We show that experimental data and theoretical evidence agree in relating Tc ( alpha ) to enhanced penetration of the triplet component of the condensate into the Co/Cu/Co spin valve in the maximally noncollinear magnetic configuration.