Superconducting Triplet Spin Valve

We study the critical temperature T(c) of SFF trilayers (S is a singlet superconductor, F is a ferromagnetic metal), where the long-range triplet superconducting component is generated at noncollinear magnetizations of the F layers. We demonstrate that Tc can be a nonmonotonic function of the angle a between the magnetizations of the two F layers. The minimum is achieved at an intermediate a, lying between the parallel (P, alpha = 0) and antiparallel (AP, alpha = pi) cases. This implies a possibility of a "triplet" spin-valve effect: at temperatures above the minimum T(c)(Tr) but below T(c)(P) T(c)(AP), the system is superconducting only in the vicinity of the collinear orientations. At certain parameters, we predict a reentrant T(c)(alpha)behavior. At the same time, considering only the P and AP orientations, we find that both the "standard" (T(c)(P) < T(c)(AP)) and "inverse" (T(c)(P) > T(c)(AP)) switching effects are possible depending on parameters of the system.