Domain wall trapping in controlled submicron ferromagnetic elements

The domain configuration in permalloy wires (30 nm thick, 10 mu m wide, and 205 mu m long) with a wide size range of a narrow central bridge (5 mu m l ong and w mu m wide; 0.5 less than or equal to w less than or equal to 10 m u m) 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 b y a small external field. Scanning magneto-optical Kerr effect revealed tha t the coercivity in these structures are the same as that in a straight wir e, suggesting that domain wall movement is the dominant process in the magn etization reversal of these structures. (C) 2000 American Institute of Phys ics. [S0021-8979(00)35408-1].