Patent ID: 7499247

Claim:
A magnetoresistive sensor comprising stacked layers, said stacked layers comprising: a first magnetic layer having a first ferromagnetic layer in which a direction of magnetization is pinned relative to an external magnetic field, a first non-magnetic intermediate layer, and a second ferromagnetic layer in which a direction of magnetization is pinned in a direction opposite to the direction of magnetization of said first ferromagnetic layer, said first ferromagnetic layer, said first non-magnetic intermediate layer, and said second ferromagnetic layer being stacked in this order; a second non-magnetic intermediate layer; and a second magnetic layer in which a direction of magnetization is variable depending on said external magnetic field, said first magnetic layer, said second non-magnetic intermediate layer, and said second magnetic layer being stacked in this order to form said stacked layers, wherein a sense current flows through said stacked layers substantially in the direction of stacking, a ratio of a layer thickness of said second ferromagnetic layer to a layer thickness of said first ferromagnetic layer is in a range between 1.4 and 1.9, and a ratio of a product of a saturation magnetization and the layer thickness of said second ferromagnetic layer to a product of a saturation magnetization and the layer thickness of said first ferromagnetic layer is in a range between 0.9 and 1.1, wherein said second ferromagnetic layer includes a layer containing nickel and iron, wherein said second ferromagnetic layer includes a partial layer stack comprising a first partial layer containing cobalt and iron, a second partial layer containing nickel and iron, and a third partial layer containing cobalt and iron, said first partial layer, said second partial layer, and said third partial layer being stacked in this order to form said partial layer stack, wherein said second ferromagnetic layer includes said partial layer stack, a third non-magnetic intermediate layer, and said partial layer stack, being stacked in this order.