Oki Electric Industry Co., Ltd.

Haruki Yamane

Yoshinori Maeno

Masanobu Kobayashi

Kayoko Sato

Juro Mita

A magnetoresistive sensor has a magnetic bias field source that generates an alternating magnetic bias field, a giant magnetoresistive sensing element positioned in the alternating magnetic bias field, and a resistance detecting circuit that detects changes in the electrical resistance of the giant magnetoresistive sensing element caused by the combined action of the alternating magnetic bias field and an external magnetic field. The alternating magnetic bias field enables small external magnetic fields to be detected with high sensitivity.

Magnetoresistive sensor and head with alternating magnetic bias field

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.

Giant magnetoresistive information recording medium, and associated

A memory cell has two magnetoresistive memory elements, each with at least two ferromagnetic layers. The electrical resistance of each memory element differs depending on whether the ferromagnetic layers are magnetized in the parallel or antiparallel state. Binary information is stored in the memory cell by supplying currents that generate magnetic fields setting one memory element to the parallel state and the other memory element to the antiparallel state. Alternatively, ternary information is stored, two of the ternary values being stored in the same way as the binary values, and the third ternary value being stored by setting both memory elements to the same state. The stored values are read by comparing the resistances of the two memory elements.

High-speed, low-current magnetoresistive memory device

A magnetic recording medium having a substrate, and an artificial superlattice deposited on the substrate as a vertical magnetization film. The artificial superlattice is a Co/Pt artificial superlattice which is composed of alternate Co and Pt layers deposited on the substrate. The magnetic recording medium is fabricated by the steps of: disposing a Co target and a Pt or Pd target separating from a substrate; performing an RF sputtering to the substrate by alternately facing the substrate with the Co target and the Pt or Pd target by means of periodical movement of the substrate, thereby forming a Co/Pt or Co/Pd artificial superlattice) on the substrate; and performing heat treatment to the Co/Pt or Co/Pd artificial superlattice at a temperature T in the range of 200.degree. C. to 450.degree. C. inclusive.

Magnetic recording medium method and apparatus for fabricating same

A magnetic recording medium having a triple layered structure including a substrate, a first layer or a soft magnetic thin film of high permeability piled on the substrate, a second layer or a vertical magnetization film piled on the first layer, a third layer or a soft magnetic film of high permeability piled on the second layer. A magnetic recording apparatus alternately switches the magnetization orientations of the second layer or the vertical magnetization film at a recording location where a latent image is to be formed. The first and third layer or the soft magnetic thin films can improve recording efficiency. The field produced by the second layer or the vertical magnetization film causes the third layer or the soft magnetic thin film to be magnetized along the surface of the magnetic recording medium, and this results in the concentration of the flux owing to switching of the magnetization directions. This enables high density recording and improves recording sensitivity and reproducing sensitivity.

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Tokyo, Japan

Haruki Yamane