Аннотация:Magnetic properties of ultrathin Pd99Fe01 films grown on niobium films are
investigated by magneto-optic visualization, SQUID magnetometry, and Hallvoltage
measurements in the temperature range from 3 to 40K. We show that the
films are ferromagnetic at thickness larger than 10 nm. The Curie temperature TC
varies from 2 to 40K with increase of film thickness to 80 nm. The value of
spontaneous magnetization of the Pd99Fe01 depends on the PdFe film thickness.
The estimated spin polarization is about 4 μB per Fe ion, which corresponds to
the polarization of the Pd3Fe compound. In contrast to the homogenous bulk
material, Pd99Fe01 films consist of ferromagnetic nano-clusters in a paramagnetic
host, which is confirmed by characteristic features of the magnetization loops
and by the increase of critical current density in the adjacent Nb layer. The size
of the clusters is estimated as 10 nm, which is in agreement with the 30%
increase of the supercurrent observed in the Nb.
