YBa2Cu3O7/La2/3Ca1/3MnO3 superconducting/ferromagnetic
(SC/FM) multilayers have been studied by neutron reflectometry. Evidence for a
characteristic difference between the structural and magnetic depth profiles is
obtained from the occurrence of a structurally forbidden Bragg peak in the FM
state. The comparison with simulated reflectivity curves allows us to identify
two possible magnetization profiles: a sizable magnetic moment within the SC
layer antiparallel to the one in the FM layer (inverse proximity effect), or a
``dead'' region in the FM layer with zero net magnetic moment. The former
scenario is supported by an anomalous SC-induced enhancement of the
off-specular reflection, which testifies to a strong mutual interaction of SC
and FM order parameters.Comment: 4 pages, 2 figures, submitted to PR