Superconducting triplet spin valve

Tuesday 20th April 2010 at 4pm

CNRS Bât E, conference room "Louis Weil" on 3rd floor

Yakov FOMINOV (Institut Landau, Moscou)

 

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 T_c can be a nonmonotonic function of the angle α between the magnetizations of the two F layers. The minimum is achieved at an intermediate α, lying between the parallel (P, α=0)  and antiparallel (AP, α=∏) cases.
This implies a possibility of a "triplet" spin-valve effect: at temperatures above the minimum T_c^Tr but below T_c^P and T_c^AP, the system is superconducting only in the vicinity of the collinear orientations. At certain parameters, we predict a reentrant T_c(α) 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.