Magnetoresistive sensor employing an exchange-bias enhancing layer with a variable-composition transition region

Abstract

An exchange-biased magnetoresistive (MR) read transducer in which the MR layer composition is changed at the interface with an antiferromagnetic layer, which is in direct contact with the ferromagnetic MR layer. The exchange-bias field strength H.sub.UA in the MR layer is increased at room temperature by adding a specially-optimized transition region in the ferromagnetic MR layer at the interface. The percentage of iron in the ferromagnetic alloy varies from a higher value at the interface to a lower value at the opposite end of the transition region. The higher iron ratio at the antiferromagnetic interface enhances the exchange-bias field H.sub.UA and the lower iron ratio throughout the bulk of the ferromagnetic MR layer maintains the lower coercivity preferred in the layer, thereby enhancing the longitudinal bias field with respect to the MR coercivity. Advantageously, the enhanced longitudinal bias effect of the special ferromagnetic transition region does not reduce the critical temperature T.sub.cr at which the temperature-dependent exchange-bias field H.sub.UA (T) approaches zero.

Dependencies are inferred from the claim text.