Spinstand demonstration of areal density enhancement using two-dimensional magnetic recording (invited)

Abstract

Exponential growth of the areal density has driven the magnetic recording industry for almost sixty years. But now areal density growth is slowing down, suggesting that current technologies are reaching their fundamental limit. The next generation of recording technologies, namely, energy-assisted writing and bit-patterned media, remains just over the horizon. Two-Dimensional Magnetic Recording (TDMR) is a promising new approach, enabling continued areal density growth with only modest changes to the heads and recording electronics. We demonstrate a first generation implementation of TDMR by using a dual-element read sensor to improve the recovery of data encoded by a conventional low-density parity-check (LDPC) channel. The signals are combined with a 2D equalizer into a single modified waveform that is decoded by a standard LDPC channel. Our detection hardware can perform simultaneous measurement of the pre- and post-combined error rate information, allowing one set of measurements to assess the absolute areal density capability of the TDMR system as well as the gain over a conventional shingled magnetic recording system with identical components. We discuss areal density measurements using this hardware and demonstrate gains exceeding five percent based on experimental dual reader components.

Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

“…Areal recording density of the granular media continues to grow significantly that recently it has already exceeded 1 Tbits/in 2 . 1 To further extend the recording density of the granular media, the reduction of media noise while maintaining the thermal stability is a critical challenge. The media noise reduction can be achieved by decreasing the magnetic grain size and the intergranular exchange coupling.…”

Effects of utilizing a granular nucleation layer on magnetic properties and microstructure of CoPt–B2O3 granular medium

“…1) The granular media have achieved a huge increase in areal recording density, surpassing 1 Tbits=in 2 . 2) To further increase the recording density of the media, reductions in magnetic grain diameter and intergranular exchange coupling 3) while enhancing the magnetocrystalline anisotropy (K u ) to reduce the medium noise and overcome the thermal stability issue are essential. Practically, for the present granular media, amorphous phase oxides that do not form a solid solution with the alloy have been used as grain boundary materials to separate magnetic grains.…”