Patent ID: 7289303

Claim:
A sensor comprising: first, second and third ferromagnetic layers that are interleaved with first and second nonferromagnetic layers, said first nonferromagnetic layer residing between said first and second ferromagnetic layers, said second nonferromagnetic layer residing between said second and third ferromagnetic layers, said first and third ferromagnetic layers having magnetic moments with directions that are fixed in response to an applied magnetic field, said second ferromagnetic layer having a free portion and a fixed portion, said free portion having a magnetic moment with a direction that rotates in response to said applied magnetic field and said fixed portion having a magnetic moment with a direction that does not rotate in response to said applied magnetic field; and first and second antiferromagnetic layers having different blocking temperatures, said first antiferromagnetic layer adjoining said first ferromagnetic layer and said second antiferromagnetic layer adjoining said third ferromagnetic layer, said second antiferromagnetic layer having a low blocking temperature and said first antiferromagnetic layer having a high blocking temperature; wherein said third ferromagnetic layer overlaps said fixed portion and does not overlap said free portion.