  Polarized neutron reflectometry is used to study the magnetic proximity
effect in a superconductor/ferromagnet (SC/FM) system of composition
Cu(32nm)/V(40nm)/Fe(1nm)/MgO. In contrast to previous studies, here a single
SC/FM bilayer, is studied and multilayer artefacts are excluded. The necessary
signal enhancement is achieved by waveguide resonance, i.e. preparing the
V(40nm)/Fe(1nm) SC/FM bilayer sandwiched by the highly reflective MgO substrate
and Cu top layer, respectively . A new magnetic state of the system was
observed at temperatures below 0.7 TC. manifested in a systematic change in the
height and width of the waveguide resonance peak. Upon increasing the
temperature from 0.7 TC to TC, a gradual decay of this state is observed,
accompanied by a 5% growth of the diffuse scattering. According to theoretical
studies, such behavior is the result of the magnetic proximity effect. Due to
the presence of the thin FM layer the superconducting electrons are polarized
and, as a result, near the SC/FM interface an additional magnetic layer appears
in the SC with thickness comparable to ksi, the coherence length of the
superconductor.
