Giant magnetoresistive information recording medium, and associated recording and reproducing method and apparatus

摘要

Information is recorded by applying weak and strong magnetic fields to a giant magnetoresistive medium having a pair of ferromagnetic layers, a nonmagnetic interlayer, and an antiferromagnetic layer. The medium preferably has a magnesium-oxide base layer, and may also have an electrode layer. The weak magnetic field magnetizes the ferromagnetic layers in the antiparallel state. The strong magnetic field magnetizes the ferromagnetic layers in the parallel state, which has lower electrical resistance than the antiparallel state. The recorded information is reproduced by detecting the electrical resistance of the medium, either between two electrodes contacting the surface of the medium, or between the electrode layer in the medium and an electrode contacting the surface of the medium.