Quantum generalized constant coupling model for geometrically frustrated antiferromagnets

A generalized constant coupling approximation for quantum geometrically frustrated antiferromagnets is presented. Starting from a frustrated unit, we introduce the interactions with the surrounding units in terms of an internal effective field which is fixed by a self consistency condition. Results for the static magnetic susceptibility and specific heat are compared with previous results in the framework of this same model for the classical limit. The range of applicability of the model is discussed.Comment: 11 pages, 6 figures, 1 Tables, typeset using RevTeX 4, small correction in Table

Magnetooptical Properties of Ce-Doped YIG Single Crystals

The Faraday rotation (FR) of cerium substituted yttrium iron gamets single crystals Y3-xCexFe5O12 (YIG:Ce) with x=0.055 has been investigated at 1152 and 632.8 nm in the 6 K - 600 K temperature range and magnetic field up to 20 kOe applied along the [111] and [100] directions. In contrast to magnetic properties, the FR of YIG:Ce is strongly different from FR of pure YIG at both wavelengths. The FR contribution of the Ce3+ ions, mainly attributed to intra-ionic electric dipole transitions between the 4f1 and 4f0 5d1 configurations, is discussed within the frame of the one-ion model of ferrimagnetic gamets

MAGNETIC PROPERTIES OF CADMIUM-COBALT FERRITE SINGLE CRYSTALS

Magnetic properties of single crystals of cobalt and substituted cadmium-cobalt spinel ferrites are presented under high magnetic field up to 180 kOe in the 4.2-300 K temperature range for five substitution rates. The easy direction of magnetization is [100] whereas abrupt field transitions are observed below 150 K for the [111] direction. The influence of the cadmium substitution on the molecular field coefficients is determined and the first results concerning the pure cadmium spinel ferrite are given

Nouvelle méthode de synthèse et propriétés de ferrite spinelle pour enregistrement magnétooptique réinscriptible

Cobalt ferrite spinels films have been synthesized by oxidizing at different temperatures of a metallic alloy film CoFe2. This metallic film is deposited on glass substrates by sputtering of a Fe target covered by Co platelets. X ray diffraction data and electron microprobe analysis show that the spinel phase CoFe2O4begins to form at 300 °C and crystallizes at higher temperatures. No preferential orientation was observed on glass substrates. Magnetic and magneto-optic properties (Faraday rotation (FR)) are a function of the oxidizing temperature Tox and particularly at 632.8 nm, FR are strongly related to the distribution of the Co2+ ions in the different sites of the spinel structure. Films prepared at Tox < 600 °C present properties close to those of bulk CoFe2O4. The high FR of the films indicate that this method could be used to synthesize Co ferrite spinel derived compounds as MO recording media

YTTERBIUM SUBLATTICE CONTRIBUTION TO THE FARADAY ROTATION OF YTTERBIUM IRON GARNET

Faraday Rotation (FR) measurements performed on single crystal Ytterbium Iron Garnet (YbIG) at 1.15 micron wavelength are presented in a magnetic field up to 20 kOe in the 6-580 K temperature range where the ferrite presents a spontaneous magnetization. The ytterbium contribution to FR is determined and briefly discussed