Feromagnetic "$π$"-junctions

Kontos, T.; Aprili, M.; Lesueur, J.; Genet, F.; Stephanidis, B.; Boursier, R.

Feromagnetic "$π$"-junctions

Authors

Description

We investigate Josephson coupling through a ferromagnetic thin film using Superconductor-Insulator-Ferromagnet-Superconductor planar junctions. Damped oscillations of the critical current are observed as a function of the ferromagnetic layer thickness. We show that they result from the exchange energy gained or lost by a quasiparticle Andreev-reflected at the ferromagnet-superconductor interface. The critical current cancels out at the transition from positive ("0") to negative ("$π$") coupling, in agreement with theoretical calculations.
4 pages, 4 figures