  Employment of the non-trivial proximity effect in superconductor/ferromagnet
(S/F) heterostructures for the creation of novel superconducting devices
requires accurate control of magnetic states in complex thin-film multilayers.
In this work, we study experimentally in-plane transport properties of
microstructured Nb/Co multilayers. We apply various transport characterization
techniques, including magnetoresistance, Hall effect, and the
first-order-reversal-curves (FORC) analysis. We demonstrate how FORC can be
used for detailed in situ characterization of magnetic states. It reveals that
upon reduction of the external field, the magnetization in ferromagnetic layers
first rotates in a coherent scissor-like manner, then switches abruptly into
the antiparallel state and after that splits into the polydomain state, which
gradually turns into the opposite parallel state.
