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Proceedings Paper

Co/Pt and Co/Pd multilayers as a new class of magneto-optical recording materials
Author(s): W. B. Zeper; Franciscus J. A. M. Greidanus; H. W. van Kesteren; Ben A. J. Jacobs; J. H. M. Spruit; Peter F. Carcia
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Paper Abstract

In this paper we give an overview of the magnetic and magneto-optical properties of Co/Pt and, to a less extent, Co/Pd multilayers as optimized for magneto-optical storage applications. The Co layers should be very thin, i.e. about 4 A , and the Pt layers about 10-20 A to achieve a 100 % remanent layer with perpendicular magnetic anisotropy and high coercivity (80-100 kA/m). Furthermore, the hysteresis loop becomes rectangular for total film thicknesses below about 20 nm. We measured the optical properties as a function of the wavelength of the light and calculated the figure of merit at three wavelengths (820, 633 and 410 nm) for various disk structures. Optimal figures of merit are obtained for film thicknesses below 20 nm, i.e. thicknesses that are optimum for the magnetic properties. The figure of merit at A. = 820 am for Co/Pt is comparable to that of GdTbFe and increases towards shorter wavelengths which favor higher-density recording. We discuss the recording performance using Lorentz images of the written domain patterns. Very regularly shaped domains can be written at normal writing conditions, i.e. at a laser power of 5-10 mW and fields of 25 kA/m. The highest carrier-to-noise ratio measured for Co/Pt is 51 dB (375 kHz carrier, 1.4 m/s, 10 kHz bandwidth). Aging experiments in dry oxygen-nitrogen atmosphere showed that Co/Pt multilayers are chemically stable up to 1 50 °C . Finally, no change in carrier-to-noise ratio is observed for Co/Pt multilayers with a Curie temperature below 300 °C after 2x104 write/read/erase cycles.

Paper Details

Date Published: 1 August 1990
PDF: 11 pages
Proc. SPIE 1274, Electro-Optic and Magneto-Optic Materials II, (1 August 1990); doi: 10.1117/12.20505
Show Author Affiliations
W. B. Zeper, Philips Research Labs. (Netherlands)
Franciscus J. A. M. Greidanus, Philips Research Labs. (United States)
H. W. van Kesteren, Philips Research Labs. (Netherlands)
Ben A. J. Jacobs, Philips Research Labs. (Netherlands)
J. H. M. Spruit, Philips Research Labs. (Netherlands)
Peter F. Carcia, E. I. DuPont de Nemours and Co (United States)

Published in SPIE Proceedings Vol. 1274:
Electro-Optic and Magneto-Optic Materials II
Hans Dammann, Editor(s)

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