Magnetic tunnel junction magnetoresistive readhead with sensing layer as rear magnetic flux guide

摘要

The magnetic tunnel junction (MTJ) magnetoresistive read head for the magnetic recording system of the present invention is an MTJ sensing layer or milk ferromagnetic having a magnetic flux guide function to direct magnetic flux from the magnetic recording medium to the tunnel junction. Has a layer. The MTJ fixed ferromagnetic layer and the MTJ tunnel barrier layer have a front edge located substantially coplanar with the sensing surface of the head. The fixed ferromagnetic layer and the free ferromagnetic layer both contact opposite sides of the MTJ tunnel barrier layer, but the free ferromagnetic layer extends beyond the rear edge of the layer closer to the sensing surface, either of the insulated tunnel barrier layer or of the rear edge of the fixed ferromagnetic layer. . This means that the magnetic flux is not zero at the tunnel junction region. The magnetization direction of the fixed ferromagnetic layer is preferably fixed in a direction generally perpendicular to the sensing surface by interfacial exchange coupling with the antiferromagnetic layer, and thus fixed in a direction perpendicular to the magnetic recording medium. The magnetization direction of the free ferromagnetic layer is aligned in a direction generally parallel to the surface of the medium when no magnetic field is applied, and freely rotates when a magnetic field is applied from the medium. The highly non-magnetizable magnetic material layer, which is longitudinally adjacent to the side of the free ferromagnetic layer, biases the magnetization of the free ferromagnetic layer in the desired direction.