Giant triplet proximity effect in superconducting pseudo spin valves with engineered anisotropy

The proximity coupling of a thin superconducting layer and an inhomogeneous ferromagnet can lead to a significant reduction of the critical temperature due to the generation of spin-polarized triplet Cooper pairs. We report critical temperature measurements of Co/Cu/NiFe(Py)/Cu/Nb superconducting pseudo spin valves (PSVs) in which the magnetization of the soft layer (Py) can be independently rotated in-plane with a magnetic field to create an angle (θ) between it and the magnetization of Co. Here we observe results consistent with spin-triplet theory and demonstrate large changes in ΔTC up to −120 mK as the Py layer is rotated from 0° (Co and Py are parallel) to 90° (Co and Py are orthogonal), which offers the potential for active control of the superconducting state. The key to this achievement is engineered magnetic anisotropy in Py, which enables well-defined control over the magnetization configuration of the PSV.The work was funded by the Royal Society, the Leverhulme Trust through an International Network Grant and the European Research Council (AIG "Superspin").This is the accepted manuscript version. The final version is available from APS at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.140508