ONE-DIMENSIONAL ENERGY BARRIER MODEL FOR COERCIVITY

The one-dimensional energy well model used to compute the coercivity of magneto-optic media based on domain-wall motion has been extended to include energy barriers. It is found that a local increase in either the anisotropy or exchange energy causes local wall pinning. In this case the wall is pinned in front of the energy barrier. When an applied field is gradually increased, the wall is pushed closer to the energy barrier, until the critical field is exceeded and a Barkhausen jump occurs. Variation of coercivity with barrier height was studied, and the results show that the coercivity increases essentially linearly with increase in height of the energy barrier. The effect of well shape on the coercivity was studied using several types of barriers of varying widths. Finally, the coercivity as a function of temperature for exchange and anisotropy barriers was computed and compared to the measured values. The results obtained in these calculations are compared with those for the well model, and it is found that by a proper choice of the dimensions of the energy barrier the coercivity obtained can approximate measured values, as in the case for the energy well model.