Observation of standard spin-switch effects in ferromagnet/superconductor/ferromagnet trilayers with a strong ferromagnet

We have measured the superconducting transition temperature Tc of ferromagnet/superconductor/ ferromagnet trilayers using Permalloy Py=Ni84Fe16 as a strongly polarized ferromagnetic material. For a parallel P or antiparallel AP alignment of the magnetization directions of the outer ferromagnets, we observe a Tc difference as large as 20 mK, with a stronger suppression of superconductivity in the P state than in the AP state. This behavior is opposite to the recent observations of Rusanov et al. Phys. Rev. B 73, 060505 2006 in Py/Nb/Py trilayers, but is consistent with earlier results on trilayers with Ni or CuNi alloy as the ferromagnetic material.