A novel strategy to improve giant magnetoresistance effect of Co/Cu multilayered nanowires arrays

Abstract

Giant magnetoresistance (GMR) effect exhibits high potential applications in ultrahigh density magnetic recording, magnetic sensors and electronic devices. Many methods were developed to improve the GMR, such as changing the diameters or content ratio of Co to Cu etc. In this work, we have successfully grown a new Co/Cu multilayered magnetic nanowires arrays (MNAs) with gradient diameter (GDMNAs). Very interestingly, we demonstrate much enhanced GMR in the GDMNAs. Moreover, it shows higher thermal stability simultaneously. This is a novel strategy to improve GMR. Generally, the diameter (d) and edge-to-edge separation (s) of MNAs play a significant role in determining the magnetic properties. If d<s, exchange interaction dominants. If d>s, dipolar interaction dominates. When we design a new GDMNAs with d<s at one end and d>s at the other, much better multilayered structures are observed on the larger end. Surprisingly, the magnetic anisotropy is found to be dominated by the portion of MNAs with d<s. Combining both properties in GDMNAs, we achieve the highest GMR value of 27% in reported Co/Cu MNAs. This design strategy not only reveals new interesting physics, which remains to be understood, but also useful to other applications based on MNAs.