Curie temperature modulated structure to improve the performance in heat-assisted magnetic recording

Abstract

We investigate how a temperature reduction in z−direction influences the switching probability and the noise in heat-assisted magnetic recording (HAMR) for a bit in bit-patterned media with dimensions d = 5 nm and h = 10 nm. Pure hard magnetic bits are considered and simulations with a continuous laser pulse are performed using the atomistic simulation tool VAMPIRE. The results display that the switching behavior shows a thermally induced exchange spring effect. Simultaneously, both the AC and the DC noise increase. Additionally, we illustrate how an artificial Curie temperature gradient within the material can compensate the HAMR performance loss due to the temperature gradient. Further, due to the graded Curie temperature, DC noise can be reduced compared to a structure where no temperature gradient is considered.

The role of interfacial intermixing on HAMR dynamics in bilayer media

“…We find that when the EBL extends over three or four monolayers the system with EBL exhibits an analogous behaviour to the intermixing case due to an effective decrease in the exchange coupling across the interface. The other, presented in supplementary note 2, is a 'linearly varying Curie temperature medium': a system whose J ij is varied linearly from J FePt ij to J Soft ij , similarly to [40]. The linear gradient of T c yields switching at temperatures larger than T FePt c and thus it proves the critical role of a local decrease in J ij rather than a linear or non-monotonic variation in J ij (T c ).…”

“…The other, presented in Supplementary note 2, is a "linearly varying Curie temperature medium": a system whose J i j is varied linearly from J FePt i j to J Soft i j , similarly to Ref. [40]. The linear gradient of T c yields switching at temperatures larger than T FePt c and thus it proves the critical role of a local decrease in J i j rather than a linear or non-monotonic variation in J i j (T c ).…”

Granular micromagnetic HAMR model: investigation of damping dependence and parametric optimization for high performance

“…The HAMR technique employs high temperatures close to the Curie temperature T c , and standard LLG is not the most appropriate choice. Meanwhile, atomistic simulations [26] have been proposed and implemented to investigate HAMR performance, such as calculations of the magnetization reversal process and the temperature dependent switching probability [19,27] to investigate designs to overcome the thermal noise limitation in HAMR [28]. Unfortunately, due to the high computational cost, the atomistic approach is not suitable for dealing with large-scale systems.…”