Evaporated Soft Bias Films
Original Publication Date: 1978-Jul-01
Included in the Prior Art Database: 2005-Feb-21
This technique produces a magnetically soft, high resistivity film for use in biasing magnetoresistive sensors by evaporation of NiFeCr alloys from a single melt. This soft film bias technique uses a magnetically soft film located above or below the sensor film. The current through the sensor saturates the bias film which in turn biases the sensor film. The sensor film and the bias film must be separated by a thin insulating film thick enough to prevent exchange coupling between the two films and thin enough for magnetic coupling between the two films. This requires the insulating film thickness to be between 200 and 500 angstroms thick. At this thickness, reliable insulation is difficult to achieve, so the bias film should have higher resistivity then the magnetoresistive sensor.