Magnetic and Read–Write Properties of Coupled Granular/Continuous Perpendicular Recording Media and Magnetization Reversal Process

Abstract

Coupled granular/continuous (CGC) media are formed by depositing a 6 nm Co/Pd multilayer onto a CoCrPt-SiO 2 granular magnetic layer. The multilayer reduces magnetic saturation field from 11.4 to 7.2 kOe. The lower is reflected in the recording overwrite (OW) improvement of around 20 dB. The thermal stability factor also increases with addition of the multilayer, from 60 to 100, resulting in the improvement of thermal stability for CGC media. The origin of the increase derives from the larger activation volume. The CGC media has coherent magnetization reversal and very weak exchange coupling, similar to the base granular media. The coherent magnetization reversal with very weak exchange coupling contributes to a signal-to-noise-ratio (SNR) improvement of around 1 dB. These results suggest that CGC media have a recording advantage over the conventional structure media, and are a promising approach to avoid the limitations of the "magnetic recording tri-lemma" and realize future ultrahigh density recording media.Index Terms-Activation volume, angular dependence of , cluster size, plane view TEM image.

Comparison of media properties between hard/soft stacked composite and capping layer perpendicular recording media

“…In current capping layer (CL) [2,3] and coupled granular/continuous (CGC) media [4], higher intergranular exchange coupling constant (A ex ) in a top magnetic layer improved the signal-to-noise ratio (SNR) and thermal stability. However, the increase in A ex also increased magnetic write width (MWW) and transition noise, which limit areal density.…”

Tailor-made nano-structured materials for perpendicular recording media and head—precise control of direct/indirect exchange coupling

“…Therefore, the required physical properties for current perpendicular recording disks and spin-valve heads are completely different from the specifications originally proposed [3]. Even though commercial HDD products using perpendicular recording systems are now available, simultaneously a fatal situation similar to that seen in longitudinal recording media, the so called trilemma occurred [4].…”

Effect of inhomogeneous microstructure of granular layer on inter granular/inter layer exchange coupling in stacked perpendicular recording media

“…[12][13][14][15] Magnetic layer which consists of CoCrPt metal rich magnetic grains and oxide rich boundary phase has inhomogeneous structure with different chemical surface energy. Inhomogeneous initial growth of CL with metal material deposited on GL with metal-oxide granular material was predicted by Nemoto et al 16 However, the experimental data regarding the growth of metal material deposited on metal-oxide granular material was not shown.…”