Coupled Granular/Continuous Media – Results and Challenges

ABSTRACTWhile the most promising longitudinal recording systems cannot surpass the theoretical limit of about 200 Gb/in2 for areal recording density and the demand for higher densities is permanently increasing, the perpendicular magnetic recording constitutes the realistic issue to the longitudinal one. The perpendicular magnetic recording offers significant advantages, the most important being stronger write and read fields, and therefore the use of media of higher anisotropy, smaller grain size, higher signal-to-noise ratio, and a better thermal stability. Unfortunately, the perpendicular recording has to cope some important physical and technological difficulties. To overcome them, many ingenious solutions were proposed. In this paper the coupled granular/continuous (CGC) media, a subtle association of the continuous and, respectively, granular media, are analysed from the viewpoint of their magnetic and recording properties. The challenges and possible improvements of CGC media are discussed.

State-of-the-Art Magnetic Hard Disk Drives

Magnetic recording has progressed dramatically over the last 50 years, with an increase of almost eight orders of magnitude in the amount of information stored per unit area of disk space.Two key enablers of this progress have been the recording medium and the read-back head.This article reviews the current state of the art in multilayer thin-film longitudinal recording media and giant magnetoresistive (GMR) read heads, with particular emphasis on the nanostructured magnetic materials that are key to today's high-performance hard disk drives.