Reentrant temperature dependence of critical current in superconductor - ferromagnet - superconductor junctions based on PdFe alloys

The magnetic and transport properties of $Pd_{0.99}Fe_{0.01}$ thin films have been studied. We have found that the Curie temperature of the films is about 20 K and the magnetic properties strongly depend on temperature below $T_{Curie}$. We have also fabricated the set of superconductor-ferromagnet-superconductor josephson junctions $Nb-PdFe-Nb$. The temperature dependence of the junctions with the ferromagnet layer thickness of about 36 nm shows the reentrant behaviour that is the evidence of the transition of the junction into the $\pi$-state.
Comment: 3 pages, 4 figures