Impact of Curie Temperature Distribution and Anisotropy Field Distribution on the User Density of HAMR Under Different Thermal Gradients

We report the effects of Curie temperature (
$T_{c}$
) distribution (
$\sigma _{T_{c}}$
) and anisotropy field (
$H_{k}$
) distribution (
$\sigma _{H_{k}}$
) on the user density (UD) of heat-assisted magnetic recording (HAMR) under two distinct thermal gradients (10 and 26 °K/nm) using micromagnetic simulation. We also estimate the transition jitter analytically and compare with our simulated results. According to our findings, UD is more sensitive to
$\sigma _{T_{c}}$
variance than
$\sigma _{H_{k}}$
variance in both high and low grain pitch media. This is because a variation in the media
$T_{c}$
substantially increases the transition jitter noise in the recording. We also demonstrate that anisotropy field variation has increased effect at lower densities, as a consequence of grain-size-limited transition jitter and number of grains per bit. Furthermore, we found that
$T_{c}$
and
$H_{k}$
variations have a similar impact on UD at greater magnetic fly heights (FHs), although the sensitivity level is lower.