Magnetoresistive head having layer structure between free and lead layers with layer structure including fixed magnetization layer
An MR element includes a free layer. Hard magnetic layers are placed on both sides of the MR element and apply a bias magnetic field to the free layer. A pair of electrode layers are placed as spaced from each other, and supplies a sense current to the free layer. Layer structures are placed between portions overlapping with the respective electrode layers in the ambilateral regions of the free layer, and the electrode layers. Each layer structure includes a nonmagnetic layer, a ferromagnetic layer, and an antiferromagnetic layer. A direction of magnetization of the ferromagnetic layer is fixed by the antiferromagnetic layer, and a magnetic thickness of the ferromagnetic layer is set greater than that of the free layer.
1. A thin film magnetic head, comprising:
a magnetoresistive element incorporating a free layer an orientation of magnetization of which varies according to an external magnetic field, and a pair of electrode layers placed so as to overlap with said free layer on both sides of said free layer and be spaced from each other, for supplying an electric current to said magnetoresistive element,
said thin film magnetic head comprising a layer structure placed between a portion overlapping with said electrode layer in each of ambilateral regions of said free layer, and said electrode layer,
wherein said layer structure comprises:
an electrically conductive, ferromagnetic layer a direction of magnetization of which is fixed;
an electrically conductive, nonmagnetic layer placed between said ferromagnetic layer and said free layer; and
an electrically conductive, antiferromagnetic layer placed between said ferromagnetic layer and said electrode layer and fixing the direction of magnetization of said ferromagnetic layer,
wherein a magnetic thickness of said ferromagnetic layer is set greater than a magnetic thickness of said free layer, and
wherein said layer structure further comprises a fixed magnetization layer placed between said antiferromagnetic layer and said electrode layer and a direction of magnetization of which is fixed in a direction opposite to the direction of magnetization of said ferromagnetic layer.
2. A thin film magnetic head according to claim 1 , wherein said free layer and said ferromagnetic layer are made of a common material and a thickness of said ferromagnetic layer is set greater than a thickness of said free layer.
3. A storage device comprising a magnetic recording medium for magnetically storing a signal, and the thin film magnetic head as set forth in claim 1 , for converting a change of a magnetic field leaking from said magnetic recording medium, into an electric signal.
4. A thin film magnetic head according to claim 1 , wherein said fixed magnetization layer includes a permanent magnet layer.
5. A thin film magnetic head according to claim 1 , wherein said fixed magnetization layer includes an electrically conductive, ferromagnetic layer a direction of magnetization of which is fixed, and
wherein said layer structure further comprises an electrically conductive, antiferromagnetic layer placed between said ferromagnetic layer included in said fixed magnetization layer, and said electrode layer and fixing the direction of magnetization of said ferromagnetic layer included in said fixed magnetization layer.
6. A thin film magnetic head assembly comprising the thin film magnetic head as set forth in claim 1 , and a flexible member to which said thin film magnetic head is attached.