Domain wall trapping in controlled submicron ferromagnetic elements

The domain configuration in permalloy wires (30 nm thick, 10 μm wide, and 205 μm long) with a wide size range of a narrow central bridge (5 μm long and w μm wide; 0.5⩽w⩽10 μm) were investigated in both their demagnetized and remanent states using magnetic force microscopy and the results were confirmed by micromagnetic calculations. At the bridge region, domain walls were found to be shifted by a small external field. Scanning magneto-optical Kerr effect revealed that the coercivity in these structures are the same as that in a straight wire, suggesting that domain wall movement is the dominant process in the magnetization reversal of these structures.