Patent ID: 8094420

Claim:
A magnetoresistive device of a 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 unit is sandwiched between them from above and below, with a sense current applied in a stacking direction, characterized in that: said 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 said first shield layer positioned below and said 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, said 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, said any other frame portion partially comprises a combination of a nonmagnetic gap layer with a bias magnetic field-applying layer, said bias magnetic field-applying layer is constructed by repetitive stacking of a multilayer unit at least twice or up to 50 times, wherein said multilayer unit comprises a nonmagnetic underlay layer and a high-coercive material layer, said nonmagnetic gap layer is designed and located such that a magnetic flux given out of said bias magnetic field-applying layer is efficiently sent out to said front frame-constituting portion, and said 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 said framework, and turns the magnetization of said front frame-constituting portion into a single domain.