DC modulation noise and demagnetizing fields in thin metallic media

Author

Tarnopolsky, Giora J. ; Tran, Lung T. ; Barany, Alexander M. ; Bertram, H. Neal ; Bloomquist, Darrel R.

Author_Institution

Hewlett-Packard Lab., Palo Alto, CA, USA

Volume

25

Issue

4

fYear

1989

fDate

7/1/1989 12:00:00 AM

Firstpage

3160

Lastpage

3165

Abstract

Measurements of noise excited in magnetic recording media by a head energized by direct current yield a peak noise when the total field in the medium equals the remanent coercivity and opposes the original sense of medium saturation. The total field is the head field and a demagnetizing field stemming from a pseudotransition pinned under the head gap. This phenomenon has been studied experimentally by examining a thickness series of thin-film media with a wide range of demagnetizing ratios and by self-consistent calculations of this magnetizing process. Measurements of replay spectra were used to calibrate the record head. The demagnetizing field is about 19% of the remanent coercivity for a demagnetizing ratio of 767 nm. It is argued that careful calibration of this noise measurement yields an accurate in situ technique to monitor disk media coercivity or head efficiency variability

Keywords

amplitude modulation; calibration; coercive force; demagnetisation; electric noise measurement; magnetic disc storage; magnetic heads; magnetic thin films; metallic thin films; DC modulation noise; calibration; demagnetizing field; head efficiency variability; magnetic recording media; pseudotransition; remanent coercivity; replay spectra; self-consistent calculations; thickness series; thin metallic media; Coercive force; Current measurement; Demagnetization; Energy measurement; Magnetic field measurement; Magnetic heads; Magnetic noise; Magnetic recording; Noise measurement; Transistors;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.34389

Filename

34389