ABSTRACT
This chapter looks at the various magnetic methods available for recording of information, including data, images, and sound. Magnetic recording can be conveniently separated into two groups of related technologies: media and recording heads. Magnetic recording tapes predated magnetic recording disks and are widely used for audio and video recording. The principles of recording on magnetic disks are similar to those of recording on magnetic tapes. Magneto-optic recording makes use of the Faraday and Kerr effects in which the direction of polarization of light is rotated in the presence of a magnetic field. The magnetic recording media must have high saturation magnetization to give as large a magnetic signal as possible during the reading process. For magnetic recording tapes and floppy disks, gamma ferric oxide has been widely used as the magnetic recording medium. Cobalt surface-modified gamma ferric oxide is preferred over gamma ferric oxide as a magnetic recording medium because it has a higher coercivity.
