Thickness Dependence of Anisotropic Magnetoresistance in CoPt Alloy Multilayer Nanowires Fabricated by Dual-Bath Electrodeposition

We investigated the dependence of anisotropic magnetoresistance (AMR) on the layer thickness and Co composition of Co-rich/Pt-rich CoPt alloy multilayer nanowires fabricated by dual-bath electrodeposition using nanoporous templates. Single-nanowire current-perpendicular-to-plane (CPP) electrical transport measurements revealed that reducing the individual layer thickness to a few nanometers significantly enhanced the AMR ratio, yielding a value that was 2.7 times higher than that of single-layer CoPt alloy nanowires. This enhancement might be attributed to increased interfacial spin-dependent scattering in the multilayer structure under CPP transport. In addition, the Co composition of the Co-rich layers had little effect on the AMR ratio in the high-field saturation region. In contrast, clear differences in AMR behavior were observed at low magnetic fields, indicating that the Co composition influenced the magnetization rotation process rather than the intrinsic anisotropic resistance. These findings elucidated the mechanisms underlying AMR enhancement in multilayer nanowires and provided insight into interface-dominated spin-dependent transport for the development of high-density magnetic sensors and magnetic memory devices.