Field dependent helical magnetic structure in a compensated Gd/Co multilayer

Abstract

Rare earth –transition metal heterostructures are known to exhibit a number of magnetic structures at different temperatures and magnetic fields due to the strong antiferromagnetic interaction at the interfaces. Using spin-dependent specular and off-specular polarized neutron reflectivity (PNR), we observed the field-dependent twisted helical magnetic structure with a planar 2π domain wall (DW) in a Gd/Co multilayer. Macroscopic magnetization measurements revealed the field-dependent compensation temperature, which increases with an increase in the applied field. Specular PNR at 5 K, after field cooling the multilayer in an applied field of 100 Oe, reveals the formation of planar 2π DWs and antiferromagnetic coupling at the interfaces. Off-specular PNR data from multilayer at 5 K also revealed the development of magnetic inhomogeneities for the central part (thickness ~ 25 Å) of each Gd layer in the multilayer. In contrast, a similar magnetic property of the multilayer was observed at a higher temperature (125 K) on applying a field of 500 Oe. The field-dependent tunability of twisted helical magnetic structures with planar 2π DWs and the development of highly correlated magnetic inhomogeneities may be key for application in spin-based technology.