Spin valve element and thin film magnetic head

Abstract

A spin valve element includes an antiferromagnetic layer, a pinned magnetic layer formed in contact with the antiferromagnetic layer so that the magnetization direction thereof is pinned by an exchange coupling magnetic field with the antiferromagnetic layer, a nonmagnetic conductive layer in contact with the pinned magnetic layer, and a free magnetic layer in contact with the nonmagnetic conductive layer. The free magnetic layer includes a nonmagnetic intermediate layer, and first and second free magnetic layers with the nonmagnetic intermediate layer provided therebetween, the second free magnetic layer is formed in contact with the nonmagnetic conductive layer, the first and second free magnetic layers are antiferromagnetically coupled with each other to bring both layers into a ferrimagnetic state, and either of the first and second free magnetic layers comprises a ferromagnetic insulating film. It is thus possible to increase the sensitivity to an external magnetic field, and suppress the occurrence of a shunt loss to increase the rate of change in magnetoresistance.

What is claimed is:  
     
         1 . A spin valve element comprising an antiferromagnetic layer, a pinned magnetic layer formed in contact with the antiferromagnetic layer so that the magnetization direction thereof is pinned by an exchange coupling magnetic field with the antiferromagnetic layer, a nonmagnetic conductive layer in contact with the pinned magnetic layer, and a free magnetic layer in contact with the nonmagnetic conductive layer; 
 wherein the free magnetic layer comprises a nonmagnetic intermediate layer, and first and second free magnetic layers with the nonmagnetic intermediate layer provided therebetween, the second free magnetic layer is formed in contact with the nonmagnetic conductive layer, the first and second free magnetic layers are antiferromagnetically coupled with each other to bring both layers into a ferrimagnetic state, and either of the first and second free magnetic layers comprises a ferromagnetic insulating film.    
     
     
         2 . A spin valve element according to    claim 1   , wherein the first free magnetic layer comprises only the ferromagnetic insulating film.  
     
     
         3 . A spin valve element according to    claim 1   , wherein the first free magnetic layer preferably comprises a laminate of the ferromagnetic insulating film and a first ferromagnetic conductive film, the first ferromagnetic conductive film is formed in contact with the nonmagnetic intermediate layer, and the ferromagnetic insulating film and the first ferromagnetic conductive film are ferromagnetically coupled with each other to bring both films into a ferromagnetic state.  
     
     
         4 . A spin valve element according to    claim 1   , wherein the first free magnetic layer comprises only the first ferromagnetic conductive film.  
     
     
         5 . A spin valve element according to    claim 3   , wherein the thickness s of the first ferromagnetic conductive film is in the range of 0 nm<s≦3.0 nm.  
     
     
         6 . A spin valve element according to    claim 1   , wherein the second free magnetic layer comprises only the ferromagnetic insulating film.  
     
     
         7 . A spin valve element according to    claim 1   , wherein the second free magnetic layer comprises a laminate of the ferromagnetic insulating film and a second ferromagnetic conductive film, the second ferromagnetic conductive film is formed in contact with the nonmagnetic intermediate layer, and the ferromagnetic insulating film and the second ferromagnetic conductive film are ferromagnetically coupled with each other to bring both films into a ferromagnetic state therebetween.  
     
     
         8 . A spin valve element according to    claim 1    or    4   , wherein the second free magnetic layer comprises a laminate of the ferromagnetic insulating film and a third ferromagnetic conductive film, the third ferromagnetic conductive film is formed in contact with the nonmagnetic conductive layer, and the ferromagnetic insulating film and the third ferromagnetic conductive film are ferromagnetically coupled with each other to bring both films into the ferromagnetic state.  
     
     
         9 . A spin valve element according to    claim 1    or    4   , wherein the second free magnetic layer comprises the ferromagnetic insulating film, and the second and third ferromagnetic conductive films with the ferromagnetic insulating film provided therebetween, which are ferromagnetically coupled with each other to bring the films into the ferromagnetic state.  
     
     
         10 . A spin valve element according to    claim 1   , wherein the second free magnetic layer comprises only the second ferromagnetic conductive film.  
     
     
         11 . A spin valve element according to    claim 1   , wherein the ferromagnetic insulating film is a ferromagnetic insulating oxide film or ferromagnetic insulating nitride film.  
     
     
         12 . A spin valve element according to    claim 11   , wherein the ferromagnetic insulating film is a ferromagnetic insulating oxide film composed of Fe—O or M—Fe—O (wherein M is at least one element of Mn, Co, Ni, Ba, Sr, Y, Gd, Cu, and Zn).  
     
     
         13 . A spin valve element according to    claim 11   , wherein the ferromagnetic insulating film is a ferromagnetic insulating oxide film comprising a mixture of a fine crystal phase of bcc structure Fe having an average crystal grain diameter of 10 nm or less and an amorphous phase containing large amounts of element M or M′ and O (wherein M represents at least one element of the rare earth elements, and M′ represents at least one element of Ti, Zr, Hf, V, Nb, Ta, and W), and the ratio of the fine crystal phase of bcc structure Fe to the entire structure is 50% or less.  
     
     
         14 . A spin valve element according to    claim 11   , wherein the ferromagnetic insulating film is a ferromagnetic insulating nitride film comprising a fine crystal phase mainly composed of bcc structure Fe having an average crystal grain diameter of 10 nm or less and an amorphous phase mainly composed of a compound of N and at least one element M selected from the group consisting of the rare earth metal elements, Ti, Zr, Hf, V, Nb, Ta, and W, and the ratio of the amorphous phase is 50% or more of the structure.  
     
     
         15 . A spin valve element according to    claim 6   , wherein the thickness u of the ferromagnetic insulating film is in the range of 0.5 nm≦u≦10 nm.  
     
     
         16 . A spin valve element comprising an antiferromagnetic layer, a pinned magnetic layer formed in contact with the antiferromagnetic layer so that the magnetization direction thereof is pinned by an exchange coupling magnetic field with the antiferromagnetic layer, a nonmagnetic conductive layer in contact with the pinned magnetic layer, and a free magnetic layer in contact with the nonmagnetic conductive layer; 
 wherein the free magnetic layer comprises a nonmagnetic intermediate layer, and first and second free magnetic layers with the nonmagnetic intermediate layer provided therebetween, the second free magnetic layer is formed in contact with the nonmagnetic conductive layer, the first and second free magnetic layers are antiferromagnetically coupled with each other to bring both layers into a ferrimagnetic state, and the second free magnetic layer comprises a nonmagnetic intermediate insulating film and a pair of ferromagnetic conductive films which are antiferromagnetically coupled with each other to bring both films into a ferrimagnetic state.    
     
     
         17 . A spin valve element comprises an antiferromagnetic layer, a pinned magnetic layer formed in contact with the antiferromagnetic layer so that the magnetization direction thereof is pinned by an exchange coupling magnetic field with the antiferromagnetic layer, a nonmagnetic conductive layer in contact with the pinned magnetic layer, and a free magnetic layer in contact with the nonmagnetic conductive layer; 
 wherein the free magnetic layer comprises a nonmagnetic intermediate insulating layer, and first and second free magnetic layers with the nonmagnetic intermediate insulating layer provided therebetween, and the first and second free magnetic layers are antiferromagnetically coupled with each other to bring both layers into a ferrimagnetic state.