Magnetoresistive device of the cpp type, and magnetic disk system

Abstract

The invention provides a magnetoresistive device of the CPP (current perpendicular to plane) structure, comprising a magnetoresistive unit, and a first, substantially soft magnetic shield layer positioned below and a second, substantially soft magnetic shield layer positioned above, which are located and formed such that the magnetoresistive effect is sandwiched between them from above and below, with a sense current applied in the stacking direction. The magnetoresistive unit comprises a nonmagnetic intermediate layer, and a first ferromagnetic layer and a second ferromagnetic layer stacked and formed such that said nonmagnetic intermediate layer is sandwiched between them. At least one of the first shield layer positioned below and the second shield layer positioned above is configured in a framework form having a planar shape (X-Y plane) defined by the width and length directions of the device. The framework has a front frame-constituting portion located on a medium opposite plane side in front and near where the magnetoresistive unit is positioned, and any other frame portion. The any other frame portion partially comprises a combination of a nonmagnetic gap layer with a bias magnetic field-applying layer. The bias magnetic field-applying layer is constructed by repeating the stacking of a multilayer unit at least twice or up to 50 times, wherein the multilayer unit comprises a nonmagnetic underlay layer and a high-coercive material layer. The nonmagnetic gap layer is designed and located such that a magnetic flux given out of the bias magnetic field-applying layer is efficiently sent out to the front frame-constituting portion. The combination of the nonmagnetic gap layer with the bias magnetic field-applying layer forms a closed magnetic path with a magnetic flux going all the way around the framework, and turns the magnetization of the front frame-constituting portion into a single domain. It is thus possible to make the domain control of the shield layers much more stable, achieve remarkable improvements in resistance to an external magnetic field, and make the operation of the device much more reliable.

Dependencies are inferred from the claim text.