Patent ID: 6927948

Claim:
A differential giant magnetoresistive (GMR) sensor, comprising: a first spin valve (SV) sensor, comprising: a first pinned layer, including: a first ferromagnetic (FM1) layer; a second ferromagnetic (FM2) layer; an antiparallel coupling (APC) layer disposed between the FM1 and FM2 layers; and a first free layer adjacent to the FM2 layer on a side opposite the APC layer; a second spin valve (SV) sensor, comprising: a second pinned layer, including: a third ferromagnetic (FM3) layer; a fourth ferromagnetic (FM4) layer; an antiparallel coupling (APC) layer disposed between the FM3 and FM4 layers; and a second free layer adjacent to the FM3 layer on a side opposite the APC layer; a metal gap layer disposed between the first and second free layers; and wherein the first and second SV sensors and the metal gap layer are disposed between nonmagnetic first and second lead layers, wherein the metal gap layer provides a read gap separating the first and second free layers by a spacing equal to the recorded magnetic half-bit length.