Heat assisted magnetic recording: Grain size dependency, enhanced damping, and a simulation/experiment comparison

Abstract

Recording simulations on heat-assisted magnetic recording (HAMR) are implemented to study the dependences of grain size and Gilbert damping on the recording performance. Modified damping and temperature shift for renormalized media cells are needed to address the non-equilibrium nature of HAMR process. It is found that using smaller grains helps reduce transition jitter but increases track width. Larger damping is also found effective in reducing the jitter. Finally, the applicability of this simulation method is corroborated by comparing with experimental results.

Noise Mitigation in Granular and Bit-Patterned Media for HAMR

“…This technique uses renormalized magnetization, anisotropy, exchange, and damping near the Curie temperature to represent the media. It has been previously shown to have good agreement with experimental data [5]. However, our previous Manuscript received July 18 calculations were based on cubic renormalized media cells of 1.5 nm length scale, and it is interesting to know how the model depends on variation of cell size.…”

“…1 shows transition jitter versus renormalized cell size with media of two average grain sizes. The renormalized input parameters that govern each cell are described in [4] and [5]. These parameters are all functions of temperature and the length scale.…”

“…particles that have an acceptable fcc-L1 0 phase transition when annealing. However, even if perfect L1 0 -FePt particles down to 3 nm in diameter with unity order parameter can be fabricated, recent theoretical predictions [9] and simulations show that thermally induced errors due to the large thermal energy of grains under recording during HAMR processes will start to cancel the benefits from using smaller grains (<5 nm) or even worsen the performance, as shown in [5] and [10] via transition jitter and medium SNR calculations, respectively. In our recent work [11], we mentioned that, in recording with granular media, exchange-coupled composite grains would be ultimately advantageous only when using FeRh as a soft assisting layer.…”

Dinamika Pembalikan Magnetisasi Nanoblock Berbasis Kobalt Teredam Kuat di Bawah Stimulasi Medan Panas

“…Salah satu sifat magnetik intrinsik penting dari sebuah media penyimpanan adalah redaman Gilbert yang menentukan gerakan presisi magnetisasi terhadap medan magnet eksternal. Banyak penelitian eksperimental menaruh perhatian besar untuk menyelidiki sifat redaman Gilbert dari berbagai material paduan magnetik dan pengaruhnya dalam perekaman magnetik (Huang & Victora, 2014;Oogane et al, 2015). Dengan pemahaman yang komprehensif terkait mekanisme kontrol pembalikan magnetisasi melalui modifikasi redaman Gilbert, maka besarnya medan magnet pembalik (medan magnet penulisan) dapat dioptimalkan untuk menghasilkan sebuah sistem yang efisien.…”