Magneto-optical materials

A. K. Zvezdin, V. A. Kotov, Modem Magneto-Optics and Magneto-Optical Materials, lOP Publishing, Philadelphia (1997), 363 pages. 

FIGURE 14.18 Schematic showing the recording, readout, and erasure processes of a magneto optic material. 

The discovery in 1976 of magneto-optic materials based on the rare earth/transition metal (RE/TM) alloys (Choudhari et al., 1976) provided a practical material system for rewritable magneto-optic recording. These materials were amorphous and thus allowed acceptable signal-to-noise ratio to be obtained. Most commercial magneto-optic films today are based on terbium iron cobalt (TbFeCO). 

Magneto-optic and magnetic disc materials DyCo, TbFeCo, garnets, sputtered magnetic media (CoNiCr alloys and their carbon overcoats). 

Magneto-optical properties of (In,Mn)As and (Ga,Mn)As have been studied in order to elucidate the origin of ferromagnetism as well as to explore the possibility of using these materials as Faraday isolators, suitable for monolithic integration with the existing semiconductor lasers. 

The excellent insulating and dielectric properties of BN combined with the high thermal conductivity make this material suitable for a huge variety of applications in the electronic industry [142]. BN is used as substrate for semiconductor parts, as windows in microwave apparatus, as insulator layers for MISFET semiconductors, for optical and magneto-optical recording media, and for optical disc memories. BN is often used as a boron dopant source for semiconductors. Electrochemical applications include the use as a carrier material for catalysts in fuel cells, electrodes in molten salt fuel cells, seals in batteries, and BN coated membranes in electrolysis cells for manufacture of rare earth metals [143-145]. 

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