Antisymmetric magnetoresistance and helical magnetic structure in compensated Gd/Co multilayer

Using spin dependent specular and off-specular polarized neutron reflectivity (PNR), we report the observation of a twisted helical magnetic structure with planar 2π domain wall (DW) and highly correlated magnetic domains in a Gd/Co multilayer. Specular PNR with polarization analysis reveals the formation of planar 2πDWs below a compensation temperature (TComp), resulting to positive exchange bias in this system. Off-specular PNR with spin polarization showed development of magnetic inhomogenities (increase in magnetic roughness) for central part (thickness ~ 25-30 Å) of each Gd layer, where magnetization is aligned perpendicular (in-plane) to an applied field. These magnetic roughness are vertically correlated and results into Bragg sheet in spin flip channel of Off-specular PNR data, which is contributing towards an antisymmetric magnetoresistance at TComp in the system. The growth and tunability of highly correlated magnetic inhomogeneities (roughness) and domain structure around TComp in combination of twisted helical magnetic structure with planar 2πDWs will be key for application in all-spin-based technology.