Magnetic recording medium with strongly anisotropic particles - has uniformly aligned components with both light and heavy magnetisation and uses alternating field for erasing prior to new record

摘要

Magnetic recording medium has uniformly aligned uniaxially strongly anisotropic particles (3) with light and heavy magnetization. One axis is of light magnetization and a number of axes is of heavy magnetization. The axis of the light magnetization has an intrinsic coercive force of less than 1900 Oersted. Initially the particle population is magnetized with a field of at least 2500 Oersted in the light magnetization axis. The residual magnetic moment of the particle population is higher than 40 per cent. of the initial residual magnetic moment after an alternating field for erasing has been introduced in one of the axes of heavy magnetization.