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Using Ensemble Waveform Analysis to Compare Heat Assisted Magnetic Recording Characteristics of Modeled and Measured Signals | IEEE Journals & Magazine | IEEE Xplore

Using Ensemble Waveform Analysis to Compare Heat Assisted Magnetic Recording Characteristics of Modeled and Measured Signals


Abstract:

Ensemble waveform analysis is used to calculate signal to noise ratio (SNR) and other recording characteristics from micromagnetically modeled heat assisted magnetic reco...Show More

Abstract:

Ensemble waveform analysis is used to calculate signal to noise ratio (SNR) and other recording characteristics from micromagnetically modeled heat assisted magnetic recording waveforms and waveforms measured at both drive and spin-stand level. Using windowing functions provides the breakdown between transition and remanence SNRs. In addition, channel bit density (CBD) can be extracted from the ensemble waveforms using the di-bit extraction method. Trends in both transition SNR, remanence SNR, and CBD as a function of ambient temperature at constant track width showed good agreement between model and measurement. Both model and drive-level measurement show degradation in SNR at higher ambient temperatures, which may be due to changes in the down-track profile at the track edges compared with track center. CBD as a function of cross-track position is also calculated for both modeling and spin-stand measurements. The CBD widening at high cross-track offset, which is observed at both measurement and model, was directly related to the radius of curvature of the written transitions observed in the model and the thermal profiles used.
Published in: IEEE Transactions on Magnetics ( Volume: 53, Issue: 2, February 2017)
Article Sequence Number: 3000406
Date of Publication: 21 September 2016

ISSN Information:


I. Introduction

Heat assisted magnetic recording (HAMR) [1] is the technology that will most likely surpass conventional magnetic recording (CMR) in terms of areal density capability (ADC). As bit sizes approach media grain diameters, ADC is primarily limited by media noise. In HAMR, a highly concentrated thermal spot produced by a laser is applied to the media using a near field transducer (NFT). Applying directed heat to the media brings the temperature of the grains close to the Curie point, which allows switching to occur at lower applied magnetic fields that would otherwise be possible. This means that materials with high magneto-crystalline anisotropy and small grain diameters can be used as the media in HAMR, thus leading to a higher ADC potential compared with CMR.

References

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