Media for 10 Gb/in.2 hard disk storage: Issues and status (invited)

Abstract

Future 10 Gb/in.2 recording densities represent submicron trackwidths and sub-100 nm bit lengths. This requires extremely small magnetic switching units and very high coercivities of the media to satisfy the signal-to-noise ratio requirements. At the same time the question of magnetic thermal stability and the lack of transducers capable of performing at these densities makes it difficult to evaluate media. An uncoupled, highly uniform magnetic grain size of about 10 nm is a compromise toward maintaining an adequately low media noise and yet maintaining magnetic stability. Here we discuss current media construction, the detrimental role of substrate roughness, the role of new media structures and alloys on microstructure and magnetic properties as well as techniques for evaluating media performance prior to the availability of the required playback heads.

Magnetic properties of cobalt and cobalt–platinum nanocrystals investigated by magneto-optical Kerr effect

“…2 In the ideal case of monodisperse magnetic anisotropy energy and aligned easy axes, a bit can be made by a single ferromagnetic particle. 3 However, there are several problems remaining to be solved before application in storage industry becomes feasible. Devices based on magnetic nanocrystals are limited by thermal fluctuations of the magnetization: due to their reduced sizes, ferromagnetic nanocrystals become superparamagnetic at room temperature.…”

Structural and magnetic properties of FePt:SiO2 granular thin films

“…2 or higher because such high densities require grain sizes of 10 nm of less; and with such a small grain size, high-anisotropy energy is needed to retain thermal stability. 7,8 Furthermore, high-density recording also requires the magnetic particles to be isolated to reduce intergrain interactions, which leads to lower media noise. In this research we investigated the structural and magnetic properties of FePt:SiO 2 granular thin films, which consist of high anisotropy FePt particles embedded in a SiO 2 matrix, and their potential for high density media.…”

Controlling the Microstructure and Magnetic Properties of Ferromagnetic Nanocrystals Produced by Ion Implantation

“…More recently, additional motivation for research in this area has been provided by the potential for creating new materials with possible applications as magnetic recording media. Single-nanocrystal-per-bit data recording would represent an important advance in the information storage capacity of such media [2]. Nevertheless, several quite stringent requirements must be met in order to achieve device-quality performance.…”