Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

High-Speed and High-Density Magneto-Optical Recording Media

IP.com Disclosure Number: IPCOM000102059D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Takayama, S: AUTHOR [+2]

Abstract

Disclosed is a material for magneto-optical (m-o) recording with the Curie temperature, Tc, more than 300 degree. Its stoichiometric composition is written by Rx(A1-aBa)yTz, where R = Tb, Dy, Gd, Nd, Pr, A = Fe, B = Co,, T = Nb, Ti, Cr, Ta, Pt, Al, and 15 < x < 25, 65 < y < 75, 5 < z < 10, 0.25 < a < 0.4.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

High-Speed and High-Density Magneto-Optical Recording Media

       Disclosed is a material for magneto-optical (m-o)
recording with the Curie  temperature,  Tc,  more than 300 degree.
Its stoichiometric composition is written by Rx(A1-aBa)yTz, where R =
Tb, Dy, Gd, Nd, Pr, A = Fe, B = Co,, T = Nb, Ti,
Cr, Ta, Pt, Al, and 15 < x < 25, 65 < y < 75,
5 < z < 10, 0.25 < a < 0.4.

      These materials show excelent read/write performance,
especially high Kerr rotation and high writing sensitivity. In
general, high  Tc M-O material has an advantage in the reading
process because of its high Kerr rotation; however, high laser power
is needed in writing process. This difficulty is overcome by
optimizing this composition such that magnetization is kept high and
coercivity decreases rapidly as temperature increases.  In Fig. 1,
the typical temperature dependence of magnetization, Kerr effect, and
coercivity for these materials is shown.

      The high Kerr rotation allow us to reduce a writing pit size in
practical use and increase the recording density. High magnetization
causes a high  demagnetization field.  In Fig. 2, C/N ratio is
plotted varying the bias field.  Pits are written even applying the
bias field in a negative direction because of the high
demagnetization field.  By using this field, we can reduce both a
bias magnetic field and a writing laser power.  This fact results in
increasing writing sensitivity.