Tailored Flux Pinning in Superconductor-Ferromagnet Multilayers with Engineered Magnetic Domain Morphology From Stripes to Skyrmions

Phys. Rev. Applied 13, 014043 (2020)

Abstract: Superconductor-ferromagnet (S/F) hybrid systems show interesting magnetotransport behaviors that result from the transfer of properties between both constituents. For instance, magnetic memory can be transferred from the F into the S through the pinning of superconducting vortices by the ferromagnetic textures.Theabilitytotailorthistypeofinducedbehaviorisimportanttobroadenitsrangeofapplication. HereweshowthatengineeringtheFmagnetizationreversalallowsthetuningofthestrengthofthevortex pinning (and memory) effects, as well as the field range in which they appear. This is done by using magnetic multilayers in which Co thin films are combined with different heavy metals (Ru, Ir, Pt). By choosing the materials, thicknesses, and stacking order of the layers, we can design the characteristic domain size and morphology, from out-of-plane magnetized stripe domains to much smaller magnetic skyrmions. These changes strongly affect the magnetotransport properties. The underlying mechanisms are identified by comparing the experimental results to a magnetic pinning model.