Experimental Observation of the Inverse Proximity Effect in   Superconductor/Ferromagnet Layered Structures
  We have studied the nuclear magnetic resonance (NMR) of 51V nuclei in the superconductor/ferromagnet thin film heterostructures Ni/V/Ni and Pd{1-x}Fe{x}/V/Pd{1-x}Fe{x} in the normaland superconducting state. Whereas the position and shape of the NMR line in the normal state for the trilayers is identical to that observed in a single V-layer, in the superconducting state the line shape definitely changes, developing a systematic distortion of the high-field wing of the resonance line. We consider this as the first experimental evidence for the penetration of ferromagnetism into the superconducting layer, a phenomenon which has been theoretically predicted recently and dubbed the inverse proximity effect. 
R. I. Salikhov, I. A. Garifullin, N. N. Garif'yanov, L. R. Tagirov, K.   Theis-Broehl, K. Westerholt, H. Zabel