Patent ID: 6865044

Claim:
A method for recording multiple magnetic levels on a magnetic recording medium comprising: providing a magnetic recording medium having a substrate and a plurality of spaced-apart magnetic islands arranged on the substrate, each island comprising at least two stacked magnetic cells and a nonmagnetic spacer layer between said at least two cells, each cell in an island being a single magnetic domain having a magnetic moment oriented in one of two opposite directions substantially perpendicular to the substrate, the cell closest to the substrate in each of the islands having a coercivity greater than the other cells in the islands; applying to an island a magnetic field greater than the coercivity of the cell farthest from the substrate to switch the orientation of the magnetic moment of said farthest cell in that island without switching the orientation of the magnetic moment of the cell closest to the substrate in that island; and applying to an island said magnetic field while heating that island to switch the orientations of the magnetic moments of all the cells in that island.