R&D: Thermal Erasure in HAMR

IEEE Transactions on Magnetics has published an article written by Ali Ghoreyshi, Douglas A. Saunders, and Chris J. Rea, Seagate Technology LLC, Bloomington, MN, USA.

Abstract: “Finite-size scaling is utilized to study the erasure mechanism in heat-assisted magnetic recording (HAMR). Predicted scaling equations are evaluated both numerically and experimentally by using the write current-assist percentage (WCAP) method. The method estimates the erasing temperature of an external magnetic field by writing and erasing magnetization patterns at different frequencies. In particular, WCAP modeling shows that the Curie temperature scales according to the time scale that the recording grain is exposed to the elevated temperature. The deviation of the erase temperature from Tc for different values of the applied field is also used to estimate the scaling behavior of the anisotropy field Hk and the critical exponent β . In addition, the Stoner–Wohlfarth model is shown to be an accurate approximation for field angle dependence of the erasing process for the FePt media. Faster roll-off in the effective field is observed at small angles for the thermal ECC media.“