Coupling of Two Superconductors through a Ferromagnet: Evidence for a π Junction

V. V. Ryazanov; V. A. Oboznov; A. Yu. Rusanov; A. V. Veretennikov; A. A. Golubov; J. Aarts

doi:10.1103/PhysRevLett.86.2427

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Coupling of Two Superconductors through a Ferromagnet: Evidence for a π Junction

V. V. Ryazanov, V. A. Oboznov, A. Yu. Rusanov, A. V. Veretennikov, A. A. Golubov, J. Aarts

DOI 10.1103/PhysRevLett.86.2427 · Physical Review Letters

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Abstract

We report measurements of the temperature dependence of the critical current, Ic, in Josephson junctions consisting of conventional superconducting banks of Nb and a weakly ferromagnetic interlayer of a CuxNi1−x alloy, with x around 0.5. With decreasing temperature Ic generally increases, but for specific thicknesses of the ferromagnetic interlayer, a maximum is found followed by a strong decrease down to zero, after which Ic rises again. Such a sharp cusp can be explained only by assuming that the junction changes from a 0-phase state at high temperatures to a π phase state at low temperatures.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown