Magnetoresistance effect device, magnetoresistance head and method for producing magnetoresistance effect device

Abstract

A magnetoresistance effect device of the present invention includes a multilayer film. The multilayer film includes an antiferromagnetic film, a first ferromagnetic film, a non-magnetic film and a second ferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer. The antiferromagnetic film comprises an α-Fe 2 O 3 film. A surface roughness of the multilayer film is about 0.5 nm or less.

What is claimed is:  
     
         1 . A magnetoresistance effect device, comprising a multilayer film, the multilayer film comprising an antiferromagnetic film, a first ferromagnetic film, a non-magnetic film and a second ferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, wherein: 
 the antiferromagnetic film comprises an α-Fe 2 O 3  film; and    a surface roughness of the multilayer film is about 0.5 nm or less.    
     
     
         2 . A magnetoresistance effect device according to  claim 1 , wherein the first ferromagnetic film comprises a Co 1−x Fe x  alloy film (0<x≦0.5, where x denotes an atomic composition ratio).  
     
     
         3 . A magnetoresistance effect device according to  claim 1 , wherein the first ferromagnetic film is formed by providing a Co 1−x Fe x  alloy layer (0<x≦0.5, where x denotes an atomic composition ratio) on an Ni—Fe alloy layer or an Ni—Fe—Co alloy layer.  
     
     
         4 . A magnetoresistance effect device according to  claim 1 , wherein a main component of the underlying layer is Pt or Au.  
     
     
         5 . A magnetoresistance effect device according to  claim 1 , wherein a thickness of the α-Fe 2 O 3  film is in a range between about 5 nm and about 40 nm.  
     
     
         6 . A magnetoresistance effect device according to  claim 1 , wherein an easy axis of the second ferromagnetic film is arranged so as to be substantially perpendicular to a direction of a signal magnetic field to be detected.  
     
     
         7 . A magnetoresistance effect device, comprising a multilayer film, the multilayer film comprising an antiferromagnetic film, a first ferromagnetic film, a non-magnetic film and a second ferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, wherein: 
 the antiferromagnetic film comprises a layered structure including an α-Fe 2 O 3  film and a second anti-ferromagnetic film.    
     
     
         8 . A magnetoresistance effect device according to  claim 7 , wherein the second antiferromagnetic film comprises an NiO film or a CoO film.  
     
     
         9 . A magnetoresistance effect device according to  claim 7 , wherein the second antiferromagnetic film is overlying the α-Fe 2 O 3  film.  
     
     
         10 . A magnetoresistance effect device according to  claim 7 , wherein the α-Fe 2 O 3  film is overlying the NiO film.  
     
     
         11 . A magnetoresistance effect device according to  claim 7 , wherein an easy axis of the second ferromagnetic film is arranged so as to be substantially perpendicular to a direction of a signal magnetic field to be detected.  
     
     
         12 . A magnetoresistance effect device, comprising a multilayer film, the multilayer film comprising an antiferromagnetic film, a first ferromagnetic film, a non-magnetic film and a second ferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, wherein: 
 the antiferromagnetic film comprises an α-Fe 2 O 3  film; and    a thickness of the α-Fe 2 O 3  film is in a range between about 5 nm and about 40 nm.    
     
     
         13 . A magnetoresistance effect device according to  claim 12 , wherein an easy axis of the second ferromagnetic film is arranged so as to be substantially perpendicular to a direction of a signal magnetic field to be detected.  
     
     
         14 . A magnetoresistance effect device, comprising a multilayer film, the multilayer film comprising a first antiferromagnetic film, a first ferromagnetic film, a first non-magnetic film, a second ferromagnetic film, a second non-magnetic film, a third ferromagnetic film and a second antiferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, wherein: 
 the first antiferromagnetic film comprises an α-Fe 2 O 3  film; and    a surface roughness of the multilayer film is about 0.5 nm or less.    
     
     
         15 . A magnetoresistance effect device according to  claim 14 , wherein an easy axis of the second ferromagnetic film is arranged so as to be substantially perpendicular to a direction of a signal magnetic field to be detected.  
     
     
         16 . A magnetoresistance effect device, comprising a multilayer film, the multilayer film comprising a first antiferromagnetic film, a first ferromagnetic film, a first non-magnetic film, a second ferromagnetic film, a second non-magnetic film, a third ferromagnetic film and a second antiferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, wherein: 
 the first antiferromagnetic film comprises a layered structure including an α-Fe 2 O 3  film and a third antiferromagnetic film.    
     
     
         17 . A magnetoresistance effect device according to  claim 16 , wherein the second antiferromagnetic comprises an Ir—Mn film.  
     
     
         18 . A magnetoresistance effect device according to  claim 17 , wherein an easy axis of the second ferromagnetic film is arranged so as to be substantially perpendicular to a direction of a signal magnetic field to be detected.  
     
     
         19 . A magnetoresistance effect device according to  claim 16 , wherein at least one of the first ferromagnetic film and the third ferromagnetic film comprises an indirect exchange coupling film.  
     
     
         20 . A magnetoresistance head, comprising: 
 a magnetoresistance effect device according to  claim 6;  and    a shield gap section for insulating the magnetoresistance effect device from a shield section.    
     
     
         21 . A magnetoresistance head, comprising: 
 a magnetoresistance effect device according to  claim 11;  and    a shield gap section for insulating the magnetoresistance effect device from a shield section.    
     
     
         22 . A magnetoresistance head, comprising: 
 a magnetoresistance effect device according to  claim 13;  and    a shield gap section for insulating the magnetoresistance effect device from a shield section.    
     
     
         23 . A magnetoresistance head, comprising: 
 a magnetoresistance effect device according to  claim 15;  and    a shield gap section for insulating the magnetoresistance effect device from a shield section.    
     
     
         24 . A magnetoresistance head, comprising: 
 a magnetoresistance effect device according to  claim 18;  and    a shield gap section for insulating the magnetoresistance effect device from a shield section.    
     
     
         25 . A method for producing a magnetoresistance effect device, the device comprising a multilayer film, the multilayer film comprising an antiferromagnetic film, a first ferromagnetic film, a non-magnetic film and a second ferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, the method comprising: 
 a first step of forming the antiferromagnetic film having a thickness in a range between about 5 nm and about 40 nm on the non-magnetic substrate directly or via the underlying layer; and    a second step of depositing, on the antiferromagnetic film, the first ferromagnetic film, the non-magnetic film and the second ferromagnetic film in this order so that a surface roughness of the multilayer film is about 0.5 nm or less, wherein    the first step comprises a step of sputtering a target whose main component is α-Fe 2 O 3 .    
     
     
         26 . A method for producing a magnetoresistance effect device, the device comprising a multilayer film, the multilayer film comprising a first antiferromagnetic film, a first ferromagnetic film, a first non-magnetic film, a second ferromagnetic film, a second non-magnetic film, a third ferromagnetic film and a second antiferromagnetic film, which are provided in this order on a non-magnetic substrate directly or via an underlying layer, the method comprising: 
 a first step of forming the first antiferromagnetic film on the non-magnetic substrate directly or via the underlying layer;    a second step of depositing, on the antiferromagnetic film, the first ferromagnetic film, the first nonmagnetic film, the second ferromagnetic film, the second non-magnetic film, the third ferromagnetic film and the second antiferromagnetic film in this order so that a surface roughness of the multilayer film is about 0.5 nm or less, wherein    the first step comprises a step of sputtering a target whose main component is α-Fe 2 O 3 .