A comparison of rapid surface and volume magnetization measurements on 50% NiFe tape with models of eddy-current-limited domain wall motion

Abstract

Drive field characteristics during rapid (0.1-7 T mu s^-1) constant-voltage magnetization reversals in HCR tapes of thickness 6, 12 and 25 mu m are reported. Four stages may be distinguished: (i) a sharp rise of instrumental origin, (ii) a fairly level 'step', (iii) a roughly linear rise that accords well with the 'saturation-wave' (SW) model, and (iv) a steep rise before saturation. Magneto-optic observation shows that the surface magnetization practically saturates at the step to SW transition. This occurs relatively earlier the faster the switch and the thicker the tape. Two models for the step stage are considered. In the first (BDM) bar domains are separated by walls that span the tape thickness. The second (SDM) consists of surface domains of roughly semi-elliptical cross-section. Both assume a detailed balance between domain wall surface tension and magnetic field pressure.