Influence of Damping Constant on Writability in Heated-Dot Magnetic Recording

We discuss the influence of the damping constant α on writability in heated-dot magnetic recording using our stochastic calculation employing the Néel-Arrhenius model with a Stoner-Wohlfarth dot, since the duration for the non-Néel-Arrhenius type is very short in the writing time and most of the writing time is the Néel-Arrhenius type. The bit error rate is calculated and the result is analyzed using the mean magnetization reversal numbers per unit time N+ and N- for the magnetization reversal in the direction opposite to the recording direction and in the recording direction, respectively. The writing improves as the N+ value decreases and the N- value increases. The N+ and N- values decrease as the α value decreases, since the attempt frequency is approximately proportional to α. The writing time when the N- value is large is rather short compared with the writing time determined by the writing field. Therefore, a magnetization reversal time that is much shorter than the writing time is needed to write data. The 1/N- value represents the stochastic magnetization reversal time under thermal agitation, and the 1/N- value is inversely proportional to α. Although the N+ value becomes small, a small α value is disadvantageous to writing.