Magnetoresistive element and magnetoresistive magnetic head, magnetic recording apparatus and magnetoresistive memory device using the same

Abstract

The present invention provides a magnetoresistive (MR) element that is excellent in MR ratio and thermal stability and includes at least one magnetic layer including a ferromagnetic material M—X expressed by M 100−a X a . Here, M is at least one selected from Fe, Co and Ni, X is expressed by X 1 b X 2 c X 3 d (X 1 is at least one selected from Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt and Au, X 2 is at least one selected from Al, Sc, Ti, V, Cr, Mn, Ga, Ge, Y, Zr, Nb, Mo, Hf, Ta, W, Re, Zn and lanthanide series elements, and X 3 is at least one selected from Si, B, C, N, O, P and S), and a, b, c and d satisfy 0.05≦a≦60, 0≦b≦60, 0≦c≦30, 0≦d≦20, and a=b+c+d.

1 . A magnetoresistive element comprising: 
 a multi-layer film comprising at least two magnetic layers and at least one non-magnetic layer interposed between the two magnetic layers,    wherein a resistance value changes with a relative angle formed by magnetization directions of the at least two magnetic layers, and    at least one of the magnetic layers includes a ferromagnetic material M—X expressed by M 100−a X a , where M is at least one element selected from the group consisting of Fe, Co and Ni, and X is expressed by X 1   b X 2   c X 3   d , where X 1  is at least one element selected from the group consisting of Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt and Au, X 2  is at least one element selected from the group consisting of Al, Sc, Ti, V, Cr, Mn, Ga, Ge, Y, Zr, Nb, Mo, Hf, Ta, W, Re, Zn and lanthanide series elements, X 3  is at least one element selected from the group consisting of Si, B, C, N, O, P and S, and a, b, c and d satisfy the following equations:   0.05≦a≦60,0≦b≦60,0≦c≦30,0≦d≦20, and a=b+c+d.     
     
     
         2 . The magnetoresistive element according to  claim 1 , wherein b and c satisfy b+c>0.  
     
     
         3 . The magnetoresistive element according to  claim 2 , wherein b and c satisfy b>0 and c>0.  
     
     
         4 . The magnetoresistive element according to  claim 1 , wherein b and d satisfy b+d>0.  
     
     
         5 . The magnetoresistive element according to  claim 4 , wherein b and d satisfy b>0 and d>0.  
     
     
         6 . The magnetoresistive element according to  claim 1 , wherein the magnetic layers comprise a free layer and a pinned layer, and the magnetization of the free layer is relatively easier to rotate by an external magnetic field than the magnetization of the pinned layer.  
     
     
         7 . The magnetoresistive element according to  claim 6 , wherein the free layer includes the ferromagnetic material M—X.  
     
     
         8 . The magnetoresistive element according to  claim 6 , wherein the pinned layer includes the ferromagnetic material M—X.  
     
     
         9 . The magnetoresistive element according to  claim 6 , wherein an absolute value of a shift magnetic field of the free layer is not more than 20 Oe, and the shift magnetic field Hint is defined by 
       Hint=(H 1 +H 2 )/2 
       where H 1  and H 2  (H 1 ≧H 2 ) are two magnetic fields indicated by the points on a magnetization-magnetic field curve (M-H curve) at which magnetization is zero, the curve showing the relationship between the magnetic field and the magnetization.  
     
     
         10 . The magnetoresistive element according to  claim 6 , further comprising an antiferromagnetic layer for suppressing magnetization rotation of the pinned layer.  
     
     
         11 . The magnetoresistive element according to  claim 1 , wherein the magnetic layer that includes the ferromagnetic material M—X is a multi-layer film comprising magnetic films, and at least one of the magnetic films includes the ferromagnetic material M—X.  
     
     
         12 . The magnetoresistive element according to  claim 11 , wherein the magnetic film that includes the ferromagnetic material M—X is in contact with the non-magnetic layer.  
     
     
         13 . The magnetoresistive element according to  claim 1 , wherein the magnetic layer that includes the ferromagnetic material M—X comprises a non-magnetic film and a pair of magnetic films sandwiching the non-magnetic film.  
     
     
         14 . The magnetoresistive element according to  claim 1 , wherein the non-magnetic layer is made of a conductive material.  
     
     
         15 . The magnetoresistive element according to  claim 14 , wherein the conductive material comprises at least one selected from the group consisting of Cu, Ag, Au, Cr and Ru.  
     
     
         16 . The magnetoresistive element according to  claim 1 , wherein the non-magnetic layer is made of an insulating material.  
     
     
         17 . The magnetoresistive element according to  claim 16 , wherein the insulating material comprises at least one selected from an oxide, a nitride and an oxynitride of Al.  
     
     
         18 . The magnetoresistive element according to  claim 1 , further comprising a pair of electrode layers for allowing current to flow perpendicular to layer surfaces of the layers.  
     
     
         19 . The magnetoresistive element according to  claim 1 , wherein the ferromagnetic material M—X has a composition gradient in a thickness direction.  
     
     
         20 . The magnetoresistive element according to  claim 1 , wherein the ferromagnetic material M—X has a crystal structure that differs from a preferential crystal structure of a material made of M at ordinary temperatures and pressures.  
     
     
         21 . The magnetoresistive element according to  claim 20 , wherein the crystal structure of the ferromagnetic material M—X includes at least one selected from fcc and bcc.  
     
     
         22 . The magnetoresistive element according to  claim 1 , wherein the ferromagnetic material M—X is formed of a mixed crystal including at least two crystal structures.  
     
     
         23 . The magnetoresistive element according to  claim 22 , wherein the mixed crystal includes at least two selected from the group consisting of fcc, fct, bcc, bct and hcp.  
     
     
         24 . The magnetoresistive element according to  claim 1 , wherein the ferromagnetic material M—X is crystalline.  
     
     
         25 . The magnetoresistive element according to  claim 24 , wherein the ferromagnetic material M—X is made of columnar crystals having an average crystal grain diameter of 10 nm or less.  
     
     
         26 . The magnetoresistive element according to  claim 1 , wherein M is expressed by Fe 1−p−q Co p Ni q , where p and q satisfy the following equations: 
       0<p<1,0<q≦0.9, and p+q< 1. 
     
     
         27 . The magnetoresistive element according to  claim 26 , wherein q satisfies 0<q≦0.65.  
     
     
         28 . The magnetoresistive element according to  claim 1 , wherein M is expressed by Fe 1−q Ni q , where q satisfies the following equation: 
       0<q≦0.95. 
     
     
         29 . The magnetoresistive element according to  claim 1 , wherein M is expressed by Fe 1−p Co p , where p satisfies the following equation: 
       0<p≦0.95. 
     
     
         30 . The magnetoresistive element according to  claim 1 , wherein X is at least one element selected from the group consisting of V, Cr, Mn, Ru, Rh, Pd, Re, Os, Ir and Pt.  
     
     
         31 . The magnetoresistive element according to  claim 30 , wherein X is Pt and a satisfies the following equation: 
       0.05≦a≦50. 
     
     
         32 . The magnetoresistive element according to  claim 30 , wherein X is at least one selected from Pd, Rh and Ir and a satisfies the following equation: 
       0.05≦a≦50. 
     
     
         33 . The magnetoresistive element according to  claim 30 , wherein X is at least two elements selected from the group consisting of V, Cr, Mn, Ru, Rh, Pd, Re, Os, Ir and Pt.  
     
     
         34 . The magnetoresistive element according to  claim 33 , wherein X is expressed by Pt b Re c , where b and c satisfy the following equations: 
       0<b<50, 0 <c≦20, a=b+c , and0.05≦a≦50. 
     
     
         35 . The magnetoresistive element according to  claim 33 , wherein X is expressed by Pt b1 Pd b2 , where b 1  and b 2  satisfy the following equations: 
       0<b 1 <50,0<b 2 <50, a=b   1   +b   2 , and0.05≦a≦50. 
     
     
         36 . The magnetoresistive element according to  claim 33 , wherein X is expressed by Rh b1 Ir b2 , where b 1  and b 2  satisfy the following equations: 
       0<b 1 <50,0<b 2 <50, a=b   1   +b   2 , and0.05≦a≦50. 
     
     
         37 . A magnetoresistive magnetic head comprising: 
 the magnetoresistive element according to  claim 1  and    a magnetic shield for suppressing a magnetic field other than that to be detected by the magnetoresistive element from penetrating into the element.    
     
     
         38 . A magnetoresistive magnetic head comprising: 
 the magnetoresistive element according to  claim 1  and    a yoke for introducing a magnetic field to be detected into the magnetoresistive element.    
     
     
         39 . A magnetic recording apparatus comprising: the magnetoresistive magnetic head according to  claim 37  or  38 .  
     
     
         40 . A magnetoresistive memory device comprising: 
 the magnetoresistive element according to  claim 1;     an information recording conductor line for recording information on the magnetoresistive element; and    an information reading conductor line for reading the information.