Model of advanced recording media: The angular dependence of the coercivity including the effect of exchange interaction

Abstract

We use a micromagnetic model based on the kinetic Monte Carlo (kMC) approach to investigate theoretically the magnetic properties of advanced recording media. The model is employed to examine the impact of the magnetostatic and exchange interaction between grains of realistic perpendicular recording media on the angular-dependent coercivity since the exchange field between grains is an important factor in recording performance. The micromagnetic model allows to take the easy axis distribution and the exchange interaction between grains into account. The results confirm the importance of exchange interaction since the variation of coercivity with angle between the applied field and the orientation of easy axis which is perpendicular to the film plane, (θ) is seen to broaden with decreasing exchange field. We show that a two-stage fitting procedure involving the separate determination of the exchange field and easy axis dispersion provides a useful tool for the characterization of media for perpendicular recording and heat assisted recording. We find excellent agreement between previous experimental results and the simulations including exchange interactions leading to estimates of the exchange coupling and easy axis dispersion.

Granular micromagnetic model for perpendicular recording media: quasi-static properties and media characterisation

“…Further details of H dip calculations can be found in Refs. [14,13]. Therefore, All magnetic grains have an intrinsic energy barrier written as the following equation…”

“…Meanwhile, the Voronoi construction can also create a more distorted structure as shown in Fig.1(b). In this work, we generate a series of microstructures with specified grain size and size distribution as found in realistic recording media [14,20,21,22]. Here, we consider specifically a CoPt-based alloy [12], although the model is also applicable to the static properties often used to characterise HAMR media.…”

“…Further details of both H dip and H ex can be found in Ref. [14]. The effect of grain size is firstly investigated by varying the diameter from 4 nm to 16 nm with a diameter step of 2 nm.…”

“…The model is based on kinetic Monte Carlo (kMC) technique [13,14]. The probability of grain switching is determined based on the Arrhenius-Néel relaxation time for stationary state.…”

Kinetic Monte Carlo simulations of the effect of the exchange control layer thickness in CoPtCrB/CoPtCrSiO granular media

“…Perpendicular recording media (PRM) used in hard disc drives (HDD) represent an important class of such materials. By characterizing the relaxation process as a sequence of quasi-equilibrium states separated by thermally assisted grain reversals, kinetic Monte Carlo (kMC) provides an alternative approach to sLLG that can be applied to study such materials [3][4][5][6][7][8][9][10][11].…”