Supersaturation of antiferromagnetically coupled multilayers: A comparative polarised neutron reflectometry study

Reflectometric methods like polarised neutron reflectometry (PNR) and synchrotron Mössbauer reflectometry (SMR) are capable of investigating the plane-perpendicular and lateral magnetic structure of multilayers (MLs). Previously, a variety of domain formation and transformation phenomena was found and systematically studied in a Fe/Cr ML of strong antiferromagnetic coupling by PNR and SMR. Growth of the primary domains on passing the bulk-spin-flop transition was established. The domains were found to revert to their native state only in a field considerably higher than the apparent saturation field, a phenomenon referred to as the supersaturation domain memory effect (SDME). We present a comparative PNR study of two antiferromagnetically coupled Fe/Cr MLs with different magnetisation curves. We show that the distribution of the layer–layer coupling rather than the magnetic structure of the Cr spacer layer is responsible for the SDME.