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

Abstract

Granular magnetic recording media with perpendicular anisotropy are the basis of information storage in hard drive. This is the case for current media and future technologies such as heat assisted magnetic recording (HAMR), microwave assisted magnetic recording (MAMR) and heated dots. It is therefore important to understand the common methods of media characterisation, which often use quasi-static magnetic measurements. A granular micromagnetic model based on the kinetic Monte Carlo (kMC) approach is developed to investigate the timescales relevant to these measurements. The model is used to investigate the effects of the microstructure and the intergranular interactions on the magnetic properties including the angular dependence of the magnetisation and the time dependence of the coercivity. The latter is shown to be strongly dependent on intergranular interactions.

Magnetization dynamics of granular heat-assisted magnetic recording media by means of a multiscale model

“…Despite HAMR being proposed and investigated for around 15 years, a complete understanding of the functioning of these devices necessary for the introduction into the market is lacking [2,[12][13][14][15][16]. Moreover, engineering the medium by combining ferromagnets with different properties [4,17] and improving the head design can yield further increase in the storage density without compromising the reliability of the device [18]. In order for HAMR to be reliable, it is necessary that grains adjacent to the targeted region are not affected during the writing process.…”

The role of interfacial intermixing on HAMR dynamics in bilayer media

“…To achieve areal density as large as 4 Tb/in 2 optimisation of both the medium properties and writing/reading mechanisms is required. A path to improve HAMR performances is to engineer the magnetic layer by coupling the hard ironplatinum (FePt) grains, characterised by large magnetic anisotropy, with grains that are soft and have higher Curie temperature (T c ) than FePt [9][10][11][12][13][14][15][16][17][18]. At temperatures close to T FePt c where FePt looses its ferromagnetic character, the softer material remains ferromagnetic with a non-zero magnetisation and a * Authors to whom any correspondence should be addressed.…”