R&D: Analytical Studies of Magnetic Domain Wall Structure in Presence of Non-Uniform Exchange Bias

AIP Advances has published an article written by Yee-Mou Kaoa, Lance Horng, and Chi-Ho Cheng, Department of Physics, National Changhua University of Education, Changhua 500, Taiwan.

Abstract: “The pinning phenomena of the domain wall in the presence of exchange bias are studied analytically. The analytic solution of the domain wall spin configuration is presented. Unlike the traditional solution, which is symmetric, our new solution could exhibit the asymmetry of the domain wall spin profile. Using the solution, the domain wall position, its width, its stability, and the depinning field are discussed analytically.“

Introduction: “Magnetic recording has been the most successful method for data storage in the last few decades. In 2008, Parkin et al. proposed a racetrack memory that has all the advantages of magnetoresistance random access memory (MRAM) and an all-metallic semiconductor free structure. Racetrack memory consists of a ferromagnetic wire where a magnetic domain wall (DW) can be injected and detected. A 180° transverse DW carries a data bit via its configuration of either north to north or south to south poles. Several directions were proposed to apply nanofabrication techniques to geometrically control the DW width and shape.2 Artificially induced defects could be used as pinning sites, while nanopatterned structures provide modification of the DW’s configuration, size, and dynamical properties. Recently, it was found that the pinning site, e.g., notch, may generate topological defects and then change the chirality and topological properties of the DW structure. The chirality of the DW will affect its trajectory in a Y-shaped wire. Topological defect pinning may not be a good option for data storage.“