Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve

TL;DR

This study demonstrates the isolation of a pure triplet superconducting spin-valve effect in a carefully optimized superconductor/ferromagnet structure, revealing the specific conditions under which triplet pairing dominates.

Contribution

The paper introduces a method to isolate and observe the pure triplet spin-valve effect by tuning the ferromagnetic layer thickness to suppress the ordinary effect.

Findings

Identification of the Py2-layer thickness where the ordinary effect is suppressed.

Observation of a minimum in T_c at orthogonal magnetization configuration.

Confirmation of a pure triplet spin-valve effect in the optimized structure.

Abstract

We have studied the proximity-induced superconducting triplet pairing in CoO$_x$/Py1/Cu/Py2/Cu/Pb spin-valve structure (where Py = Ni$_{0.81}$Fe$_{0.19}$). By optimizing the parameters of this structure we found a triplet channel assisted full switching between the normal and superconducting states. To observe an "isolated" triplet spin-valve effect we exploited the oscillatory feature of the magnitude of the ordinary spin-valve effect $\Delta T_c$ in the dependence of the Py2-layer thickness $d_{Py2}$. We determined the value of $d_{Py2}$ at which $\Delta T_c$ caused by the ordinary spin-valve effect (the difference in the superconducting transition temperature $T_c$ between the antiparallel and parallel mutual orientation of magnetizations of the Py1 and Py2 layers) is suppressed. For such a sample a "pure" triplet spin-valve effect which causes the minimum in $T_c$ at the orthogonal configuration of magnetizations has been observed.