THIN FILM MAGNETORESISTIVE SENSOR

摘要

1534735 Magnetoresistive heads INTERNATIONAL BUSINESS MACHINES CORP 6 Oct 1976 [18 Nov 1975] 41550/76 Heading G5R A magnetoresistive read head comprises a magnetoresistive thin film layer 50 deposited upon a smooth substrate 52, a thin film layer 66 of nonmagnetic electrically conductive material deposited directly on layer 50, and a thin film layer 56 of a magnetic electrically conductive material deposited directly on layer 66 to produce a bias field in the MR layer 50 in operation, the layer 66 having a higher electrical resistivity than layer 56. MR layer 50 may be of permalloy Ni-Fe between 200 and 600 Angstroms thick deposited by evaporation at a substrate temperature of about 250‹ C. on to dielectric layer 52, e.g. glass. Shunt layer 66 may be of 100 to 200 Angstrom thick titanium deposited on to layer 50 at room temperature. Bias layer 56 may be 140 to 425 Angstroms thick of magnetically soft or hard material such as Ni-Fe, e.g. permalloy, or Co-Cr alloy. The sandwich 50, 66, 56 is etched to a U-shape with electrical leads 68, 70 on the legs thereof, or the sandwich may be rectangular with the leads 68, 70 stepping over it. When layers 50 and 56 are of the same material, layer 56 should be thinner than layer 50, e.g. in the ratio 0À707 to 1, so that current through layer 50 produces a magnetic field saturating layer 56, whereby layer 56, the field from which biases the MR layer 50, does not exhibit the magnetoresistive effect.