Magnetoresistive element in which pinned magnetization layers have antiparallel pinned directions, magnetic head and magnetic recording/reproducing apparatus

A magnetoresistive element, comprising:

• a magnetoresistive film;
• and
• a pair of electrodes electrically connected to upper and lower surfaces of the magnetoresistive film, respectively, so as to flow a sense current in a direction substantially perpendicular to a plane of the magnetoresistive film,
• in which the magnetoresistive film comprises:
• a first magnetization free layer of a ferromagnetic film whose magnetization direction is changed in response to the external magnetic field,
• a second magnetization free layer of a ferromagnetic film whose magnetization direction is changed in response to the external magnetic field,
• a first magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,
• a second magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,
• a third magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,
• a fourth magnetization pinned layer of a ferromagnetic film whose magnetization direction is substantially pinned in one direction,
• a first nonmagnetic intermediate layer formed between the first magnetization free layer and the first magnetization pinned layer,
• a second nonmagnetic intermediate layer formed between the first magnetization free layer and the second magnetization pinned layer,
• a third nonmagnetic intermediate layer formed between the second magnetization free layer and the third magnetization pinned layer, and
• a fourth nonmagnetic intermediate layer formed between the second magnetization free layer and the fourth magnetization pinned layer,
• the second magnetization pinned layer and the third magnetization pinned layer being formed between the second nonmagnetic intermediate layer and the third nonmagnetic intermediate layer;
• the pinned direction of magnetization of the first magnetization pinned layer is substantially parallel to the pinned direction of magnetization of the second magnetization pinned layer, the pinned direction of magnetization of the third magnetization pinned layer is substantially parallel to the pinned direction of magnetization of the fourth magnetization pinned layer, and the pinned direction of magnetization of the second magnetization pinned layer is substantially antiparallel to the pinned direction of magnetization of the third magnetization pinned layer.