Magnetoresistive magnetic recording head with permalloy sensor layer deposited with substrate heating

摘要

A magnetoresistive sensor for use as the read sensor in magnetic recording disk drives uses a permalloy (approximate composition of Ni81,Fe19) sensor layer with a magnetoresistance coefficient significantly greater than prior art permalloy sensor layers for a range of permalloy film thicknesses. The permalloy film is deposited on a substrate, such as alumina, that is essentially non-reactive with permalloy at elevated temperatures while the substrate is heated. The permalloy films have a zero or slightly negative magnetostriction, low easy and hard axis coercivities, and a low anisotropy field. At very small film thicknesses the permalloy films formed with substrate heating exhibit an even greater percentage increase in magnetoresistance coefficient than at higher film thicknesses, thereby allowing the films to function in magnetic recording disk drive heads for use at very high linear recording densities. The precise composition of the Ni-Fe alloy forming the sensor layer can be varied slightly, depending on the film thickness, to provide a sensor layer with essentially zero or slightly negative magnetostriction.