Transformation of Magnetic State under the Influence of Superconductivity in Epitaxial V/Pd1?x Fe x Bilayers

We have performed ferromagnetic resonance (FMR) studies of epitaxial V/Pd_1−x Fe _x (001) bilayers with a V thickness of the order of 40 nm and with a Pd_1−x Fe _x thickness in the range from 0.8 to 4.4 nm. For a bilayer with a Pd_1−x Fe _x thickness of 1.2 nm and x = 0.03, the FMR measurements revealed a decrease in the effective magnetization 4πM _eff of the ferromagnetic layer below the superconducting transition temperature of vanadium. As a possible explanation for this decrease, we suggest a spatial modulation of the ferromagnetic order in the Pd_1−x Fe _x layer due to modifications of the indirect exchange interaction of magnetic ions via conduction electrons in the superconducting state. A comparison with a recent theoretical investigation supports this possibility.