Individual domain wall manipulation in a local oersted circular field*

Understanding domain wall (DW) motion in nanoscale ferromagnetic structures reveals intriguing physics, with potential applications in nanoscale devices and DW data storage. One challenge is to create and move individual DWs in arbitrary locations. We developed a technique to generate localized circular magnetic field by applying a current through the tip of the atomic force microscope (AFM) and thereby manipulating the state of ferromagnetic rings [1]. Now we extend our ability to control domain walls in various structures, such as straight wires with notches and zigzag wires. By placing the tip near a 180 DW in a vertex of a zigzag wire, we can move the 180 DW along the wire and form a stable 360 DW in nearby vertex. We can also move 360 DWs with the local magnetic field around the AFM tip. We will discuss simulations and experimental implementations. \\[4pt] [1] T. Yang, N. R Pradhan, A Goldman, A. Licht, Y. Li, M T. Tuominen and K. E. Aidala, Applied Physics Letter, http://apl.aip.org/resource/1/applab/v98/i24/p242505\_s1 98, 242505, (2011)