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.