Characterization of GMR nonlinear response and the impact on BER in perpendicular magnetic recording

Akihiko Takeo, Tomoko Taguchi, Yuji Sakai, Yoichiro Tanaka

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The giant magnetoresistive (GMR) reader nonlinear response in perpendicular magnetic recording should be characterized and studied for the impact on bit-error-rate (BER) performance, because a waveform of perpendicular recording is influenced by GMR nonlinearity differently from longitudinal recording. In this study, the read/write characteristics and BER performance under the influence of GMR nonlinearity were investigated. For a GMR saturation parameter, the amplitude ratio of the fifth harmonic spectrum of isolated patterns to same spectrum of di-bit pattern was measured. This saturation parameter is a good indicator to estimate GMR saturation. GMR asymmetry has a different impact on BER performance from GMR saturation. The raw isolated waveform of perpendicular recording is inappropriate to estimate GMR asymmetry because it does not indicate an accurate de-ground level with the low-frequency cutoff channel. A specific test patterns which can provide de-ground level, was found. The measured asymmetry of this test pattern correlates closely with the asymmetry of measured GMR transfer curves. The peak shift of a differential waveform is also a good indicator to estimate GMR asymmetry. Signal processing simulation and some measurement results showed BER performance is influenced by GMR nonlinear response. The impact of GMR nonlinearity on BER depends on their feature. GMR asymmetry has a strong correlation with BER performance.

Original languageEnglish
Pages (from-to)2582-2584
Number of pages3
JournalIEEE Transactions on Magnetics
Volume40
Issue number4 II
DOIs
Publication statusPublished - 2004 Jul 1
Externally publishedYes

Keywords

  • Asymmetry
  • Giant magnetoresistive (GMR)
  • Nonlinear response
  • Perpendicular magnetic recording
  • Saturation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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