The structural and magnetic properties of Mn in Co/Mn (001) multilayers were investigated by x‐ray scattering, by magneto‐optical Kerr effect measurements, and with a Faraday balance. The multilayers were deposited by rf‐sputtering on MgO(001) substrates. Small angle x‐ray reflectivity scans and high angle Bragg scattering confirmed good layer quality and crystal coherence properties. In‐ and out‐of‐plane x‐ray scattering revealed a coherent growth of face‐centered‐cubic (fcc) (or fct) Mn on fcc Co(001). The stability limit of the metastable fct Mn structure is about 20 A˚ or 10 atomic layers. The magnetic exchange coupling appears to be partly antiferromagnetic with a first maximum located between 20 and 30 A˚. Saturation magnetization measurements indicate no ferromagnetic moment for the fct Mn layers. Furthermore, the saturation moment per unit volume is reduced as compared to the bulk Co value, suggesting the presence of ‘‘dead layers’’ at the Co/Mn interfaces. ©1995 American Institute of Physics.