Josephson junction through a thin ferromagnetic layer: negative coupling.
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 ("pi") coupling, in agreement with theoretical calculations.
Kontos
T
T
CSNSM-CNRS, Université Paris-Sud, 91405 Orsay Cedex, France.
Aprili
M
M
Lesueur
J
J
Genêt
F
F
Stephanidis
B
B
Boursier
R
R