Abstract
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 (\ensuremath{\theta}) between it and the magnetization of Co. Here we observe results consistent with spin-triplet theory and demonstrate large changes in $\ensuremath{\Delta}{T}_{C}$ up to \ensuremath{-}120 mK as the Py layer is rotated from 0\ifmmode^\circ\else\textdegree\fi{} (Co and Py are parallel) to 90\ifmmode^\circ\else\textdegree\fi{} (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.
Highlights
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
Superconducting materials are attractive for spintronic circuits as interconnects for transmitting spinpolarized quasiparticle currents [2,3], the real breakthrough would be the creation of devices which exploit the spin of triplet Cooper pairs [4]
Summary
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 TC 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.
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