Method for fabricating a magnetoresistive head
There is provided a magnetoresistive head which can realize high sensitivity and low noise even when the reading track is being reduced. Longitudinal biasing is performed to a ferromagnetic free layer whose magnetization is rotated according to an external magnetic field by providing unidirectional magnetic anisotropy by exchange coupling to an antiferromagnetic layer. A hard magnetic film is arranged at the edge of a magnetoresistive film to reduce an effective reading track width.
1. Method for fabricating a magnetoresistive head comprising:
making a magnetoresistive element having a first ferromagnetic layer, a second magnetic layer, a nonmagnetic conductive layer or a nonmagnetic tunneling barrier layer formed between said first ferromagnetic layer and said second ferromagnetic layer, a first antiferromagnetic layer formed on the first ferromagnetic layer opposite to the nonmagnetic conductive layer or a nonmagnetic tunneling barrier layer, and a second antiferromagnetic layer formed on the second ferromagnetic layer opposite to the nonmagnetic conductive layer or a nonmagnetic tunneling barrier layer,
wherein a blocking temperature T B1 of the first antiferromagnetic layer is higher than a blocking temperature T B2 of the second antiferromagnetic layer,
providing unidirectional magnetic anisotropy to the first ferromagnetic layer by the first antiferromagnetic layer, by heating higher than T B2′ and applying a magnetic field enough to saturate a magnetization direction of the first ferromagnetic layer in the element height direction,
providing unidirectional magnetic anisotropy to the second ferromagnetic layer by the second antiferromagnetic layer, by heating lower than T B1′ and applying a magnetic field enough to saturate a magnetization direction of the second ferromagnetic layer in the track width.
2. Method for fabricating a magnetoresistive head according to claim 1 , wherein the magnetoresistive element has a hard magnetic film formed so as to provide a magnetic field to the second ferromagnetic layer.
3. Method for fabricating a magnetoresistive head according to claim 1 , wherein the magnetoresistive element has a pair of electrodes for flowing a sense current to the magnetoresistive element.
4. Method for fabricating a magnetoresistive head according to claim 1 , wherein the magnetoresistive element has a flux guide for guiding an external magnetic field to the second ferromagnetic layer.
5. Method for fabricating a magnetoresistive head according to claim 4 , wherein the magnetoresistive element has a third antiferromagnetic layer arranged so as to provide unidirectional magnetic anisotropy to the magnetic flux guide.
6. Method for fabricating a magnetoresistive head according to claim 5 , wherein a blocking temperature of the third antiferromagnetic layer is T B3′ providing the unidirectional magnetic anisotropy to the first ferromagnetic layer, the second ferromagnetic layer and the third ferromagnetic layer to annealing tin the magnetic field under conditions of a temperature set from high to low in order of decreasing blocking temperature.