Microscopic magnetic structure of cuprate/manganite superlattices

Superconductivity and ferromagnetism are conventionally distinguished by mutually incompatible order parameters. However, the proximity of those materials in the artificially fabricated nanofilms of $\mathrm{YBa_2Cu_3O_7/La_{2/3}Ca_{1/3}MnO_3}$ (HTSC/FM) gives rise to new phenomena that do not exist in the isolated materials. We report on the first microscopic magnetization measurements by means of neutron reflectivity and resonant X-ray absorption. Our experimental results are consistent with the recently predicted "inverse" magnetic proximity effect. The analysis of neutron reflectivity data allows us to identify a likely magnetization profile, namely a sizable magnetic moment within the SC layer coupled antiferromagneticaly to the one in the FM layer. The scenario is supported by an anomalous superconductivity-induced enhancement of the off-specular reflection and by x-ray absorption, which testify to a strong mutual interaction of SC and FM order parameters.