Vector recording properties of perpendicular media

Summary form only given. Micromagnetic simulations of perpendicular recording media presented at MMM01 (J.J. Miles et al, 2001) demonstrated that the switching time decreases significantly when the external field is applied at an angle to the perpendicular. In a recording system the following factors must also be considered: (1) to maximise media thermal stability for a given write head field it is necessary to maximise the ratio K/sub 1//H/sub C/; (2) good overwrite performance requires H/sub S//H/sub C/ to be low (where H/sub S/, the saturation field, is the field required to reverse the magnetization of the most difficult grain); (3) the magnetization gradient in written transitions can be increased by maximising dM/sub Y//dH|/sub /spl theta/=/spl theta/´/, where /spl theta/´ is the angle of the head field at the transition center. Micromagnetic predictions of the coercivity, saturation field and the susceptibility are shown which suggest that improved recording performance should be obtained with the field applied at an angle to the perpendicular. At the leading and trailing edge of the pole, the field is at an angle to the perpendicular, and the magnetization will reverse faster and at a lower field than directly under the pole. Therefore perpendicular recording can be considered to be a vector process. The paper shows how dispersion of media characteristics determines the micromagnetic predictions, discusses the role of field gradients and shows the use of saturation curves in predicting recording performance.