Magnetic structures of SmCo/Fe bilayers during remagnetization and after mu
ltiple field cycling are studied magneto-optically (MO). Rotation of the re
manent magnetization in the soft Fe layer away from the easy axis is found
after large enough remagnetizing fields. This is indicative of the appearan
ce of biquadratic coupling between the layers. It is explained by the fluct
uation exchange mechanism due to the field induced magnetic inhomogeneity o
f the hard layer. Such an inhomogeneity revealed in the MO patterns also ex
plains the degradation of the bias field in exchange springs.