DYNAMIC MAGNETIZATION CHANGES IN LAMINATED PERMALLOY-FILMS

Laminated soft magnetic films separated by nonmagnetic interlayers have edge curling walls (ECW) at the pattern edge. The authors have investigated dynamic magnetization changes near the ECW in strip shaped laminated permalloy films. Observation results obtained by scanning Kerr effect microscope at 10 MHz show the unique magnetization behavior; that is inactive (weak Kerr signal) regions at the strip edges and magnetization change peaks inside the inactive regions. The edge region is observed as the inactive region under an excitation field smaller than the switching field in the ECW. According to the magnetization change calculation, the peak appears, because the magnetization near the ECW shows a different behavior, depending on the external field direction. Further examination shows that the ratio of the active region width in the actual strip width is changed by the layer configuration. In the 2 Oe excitation field, these ratios are estimated to be about 0.4 and 0.8 for the 50 nm / 20 nm and 25 nm / 10 nm laminated, 3 mu m widestrips, respectively. This unique magnetization behavior near the strip edges is important, when designing a narrow track head, because it determines the effective track width.