Magnetic and magneto-optical properties of rare-earth transition-metal alloys containing Dy, Ho, Fe, Co

Journal Article · Fri Mar 01 00:00:00 EST 1991 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.348561· OSTI ID:6260869

Hansen, P; Klahn, S; Clausen, C; Much, G; Witter, K ^[1]

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1. Philips GmbH Forschungslaboratorium Hamburg, Vogt-Koelln-Strasse 30, D-2000 Hamburg 54, Federal Republic of Germany (DE)

Amorphous rare-earth transition-metal alloys of composition RE{sub l{minus}{ital x}}TM{sub {ital x}} with RE=Dy, Ho; TM=Fe,Co and 0{lt}{ital x}{lt}1 and Dy{sub l{minus}{ital x}}(Fe,Co){sub {ital x}} were prepared by evaporation. The saturation magnetization, uniaxial anisotropy, coercivity, and Faraday rotation were investigated as a function of composition and temperature. Also, the spectral variation of the Kerr rotation was measured. The magnetization data indicate a strong dispersion of the RE moments due to randomly oriented local crystal field axes. The strong turndown of the Curie temperature for the Fe-rich alloys suggests that an additional dispersion is present in the Fe subnetwork. The mean field theory was used to analyze the temperature variation of the magnetization yielding smaller TM spin values and exchange coupling constants as compared with those of the Gd and Tb analogs. The uniaxial anisotropy constant {ital K}{sub {ital u}} for Dy-Co based alloys was found to vary with the square of the Dy subnetwork magnetization as predicted by the random single-ion theory. The anisotropy of Dy-Fe and Ho based alloys require additionally dipolar terms to account for the measured temperature dependence of {ital K}{sub {ital u}}. The coercive field {ital H}{sub {ital c}} follows a relation {ital H}{sub {ital c}} {similar to} {ital K}{sup 1.5}{sub {ital u}}/{ital M}{sub {ital s}}. The magneto-optical effects are primarily caused by the transition metals and therefore their compositional, temperature, and spectral dependence correspond to that of their Gd and Tb analogs. Optical recording experiments on Dy-FeCo disks yield good write and erase sensitivities and carrier-to-noise ratios up to 60 dB which are comparable to those of GdTb-Fe and Tb-FeCo disks.

• OSTI ID: 6260869
• Journal Information: Journal of Applied Physics; (USA), Vol. 69:5; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT ALLOYS
MAGNETIC PROPERTIES
DYSPROSIUM ALLOYS
HOLMIUM ALLOYS
IRON ALLOYS
AMORPHOUS STATE
ANISOTROPY
FARADAY EFFECT
FILMS
MAGNETIC STORAGE DEVICES
MAGNETIZATION
MAGNETO-OPTICAL EFFECTS
MEAN-FIELD THEORY
TEMPERATURE DEPENDENCE
VAPOR DEPOSITED COATINGS
ALLOYS
COATINGS
MEMORY DEVICES
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
360104* - Metals & Alloys- Physical Properties