Magnetizations of pinned and free layers of a spin valve sensor set by sense current fields

Claim 1

A self-biasing magnetoresistive (MR) spin valve sensor for use in a magnetic head having an air bearing surface (ABS), comprising: first and second ferromagnetic layers and a non-magnetic conductive spacer layer, each of the first and second ferromagnetic layers and the spacer layer having first and second edges which are substantially parallel to said ABS and third and fourth edges which are substantially perpendicular to the ABS; the spacer layer being sandwiched between the first and second ferromagnetic layers; first and second leads electrically connected to the third and fourth edges respectively of the first and second ferromagnetic layers and the spacer layer for conducting a sense current therethrough; the first and second ferromagnetic layers being magnetically coupled so that a ferromagnetic coupling field (H FC ) is produced in each of the first and second ferromagnetic layers; the second ferromagnetic layer having a stray demagnetization field H DEMAG which is induced into the first ferromagnetic layer; first and second flux guides; and the first flux guide being magnetically coupled to the first edges of the layers and the second flux guide being magnetically coupled to the second edges of the layers for reducing the induced stray demagnetization field H DEMAG in the first ferromagnetic layer to such an extent that when the sense current is conducted a sense current field from the first ferromagnetic layer will supplement the ferromagnetic coupling field in the second ferromagnetic layer to pin its magnetization and a sense current field from the second ferromagnetic layer will oppose the ferromagnetic coupling in the first ferromagnetic layer to permit a magnetization of the first ferromagnetic layer to be free to rotate under the influence of an applied field.