Shield design for magnetic recording head

Abstract

A magnetic shield in which all domain patterns and orientations are stable and which are consistently repeated each time said shield is exposed to an initialization field, is disclosed. This has been achieved by giving it a suitable shape which ensures that all closure domains can align themselves at a reduced angle relative to the initialization direction while still being roughly antiparallel to one another. Most, though not all, of these shapes are variations on trapezoids.

1 . A method to stabilize any one of a plurality of magnetic shields, in a magnetic head having an ABS, during exposure of said shields to an initializing magnetic field having a direction, comprising:
 giving said shield a shape selected from the group consisting of trapezoids, modified trapezoids, assisted trapezoids, hexagons, irregular octagons, notched quadrilaterals, and trapezoids modified to have reduced contact with the ABS;   ensuring thereby that all closure domains can align themselves at a reduced angle relative to said initialization direction while still being roughly antiparallel to one another thereby ensuring the presence of only one domain at each non-parallel edge, and reducing the likelihood of embedded diamond domain formation; and   whereby all domain patterns and orientations within said shield are consistently repeated each time said shield is exposed to an initialization field.   
   
   
       2 . The method of  claim 1  wherein said shape is a trapezoid, one of whose parallel edges is coplanar with the ABS and wherein both said trapezoid's non-parallel edges converge towards the ABS. 
   
   
       3 . The method of  claim 2  wherein angles between said parallel and non-parallel edges range from −60 to +60 degrees and said trapezoid has a mean width to height ratio of between about 0.5 and 10. 
   
   
       4 . The method of  claim 1  wherein said shape is a trapezoid, one of whose parallel edges is coplanar with the ABS and wherein both said trapezoid's non-parallel edges diverge away from the ABS. 
   
   
       5 . The method of  claim 4  wherein angles between said parallel and non-parallel edges range from −60 to +60 degrees and said trapezoid has a mean width to height ratio of between about 0.5 and 10. 
   
   
       6 . The method of  claim 1  wherein said shape is a modified trapezoid having a first edge that is coplanar with the ABS over said first edge's entire length, second and third edges that are not parallel to one another and that are connected to said first edge, a fourth edge comprising a central part that is parallel to said first edge, and a pair of opposing outer parts, each outer part further comprising a first sub-part that extends away from said first edge and a second sub-part that connects said first part to said second or said third edge, whichever is closest. 
   
   
       7 . The method of  claim 6  wherein each of said outer parts has a maximum separation from said first edge that is at least 1.02 times said central part's distance from said first edge. 
   
   
       8 . The method of  claim 1  wherein said shape is a modified trapezoid having a first edge that is coplanar with the ABS over its entire length, two second opposing edges that are not parallel to one another and that are connected to said first edge, and a third edge comprising a central part, parallel to said first edge, connected to a pair of opposing outer parts, that are parallel to said first edge and further therefrom than said central part, each of said outer parts being connected to one of said second edges. 
   
   
       9 . The method of  claim 8  wherein each of said outer parts is at a maximum distance from said first edge that is at least 1.02 times said central part's distance from said first edge. 
   
   
       10 . The method of  claim 1  wherein said shape is a modified trapezoid having a first edge that is coplanar with the ABS over its entire length, two second opposing edges that are not parallel to one another and that are connected to said first edge, and a curved edge whose end points each connect to one of said second edges, said curved edge having a center point whose distance to said first edge is less than either of said end point's distance to said first edge. 
   
   
       11 . The method of  claim 10  wherein each of said end points has a maximum distance from said first edge that is at least 1.02 times said center point's distance from said first edge. 
   
   
       12 . The method of  claim 1  wherein said shape is a trapezoid, having a first edge that is coplanar with the ABS, a second edge parallel to said first edge, and a pair of secondary shields having edges that are parallel to, and coplanar with, said second edge, separated therefrom by no more than the shield's height, whereby said secondary shields serve to assist nucleation of domains in said magnetic shield. 
   
   
       13 . The method of  claim 1  wherein said shape is a hexagon having a first edge that is coplanar with the ABS, a second edge parallel to said first edge, a pair of opposing third edges connected to opposing ends of said first edge, and a pair of opposing fourth edges that connect said opposing ends of said second edges to said third edges. 
   
   
       14 . The method of  claim 13  wherein said hexagon has a width to height ratio of between about 0.25 and 5. 
   
   
       15 . The method of  claim 1  wherein said shape is an irregular octagon having a first edge that is coplanar with the ABS, a second edge, longer than and parallel to, said first edge, a pair of opposing third edges, normal to said ABS, connected to opposing ends of said first edge, and a pair of opposing fourth edges, normal to said ABS, connected to opposing ends of said second edge, and a pair of fifth opposing edges that connect said second and fourth edges. 
   
   
       16 . The method of  claim 15  wherein separation between said fourth edges is between about 0.25 to 5 times separation between said first and second edges. 
   
   
       17 . The method of  claim 1  wherein said shape is an irregular hexagon having a first edge that is coplanar with the ABS and has a first width, a second edge, longer than and parallel to, said first edge and having a second width, a pair of opposing third edges, normal to said second edge, connected to opposing ends of said second edge, and a pair of fourth opposing edges that connect third edges to opposing ends of said first edge. 
   
   
       18 . The method of  claim 17  further comprising reducing said first width, relative to said second width, by inserting opposing edge cut features between said first and fourth edges. 
   
   
       19 . The method of  claim 1  wherein said shape is a notched quadrilateral having a pair of parallel first edges, one of which is coplanar with the ABS, and a pair of second edges, separated by a distance and connecting said first edges to each other, each second edge further comprising multiple collinear sub-edges connected through an odd number of inwardly facing V-shaped notches, both second edges having the same number of notches and no notch having a depth that exceeds 10% of said distance between said second edges. 
   
   
       20 . The method of  claim 1  wherein said shape is a trapezoid modified so that one of its parallel edges further comprises a central section that is coplanar with the ABS and that is shorter than its opposing parallel edge and a pair of outer sections that connect said central section to said trapezoid's non-parallel edges, said outer sections being further from said ABS than said central section. 
   
   
       21 . A magnetic shield, for use in a magnetic read-write head, comprising:
 said shield having a shape selected from the group consisting of trapezoids, modified trapezoids, assisted trapezoids, hexagons, irregular octagons, notched quadrilaterals, and trapezoids modified to have reduced contact with the ABS;   all closure domains in said shield being able to align themselves at a reduced angle relative to an initialization direction while still being roughly antiparallel to one another, thereby ensuring the presence of only one domain at each non-parallel edge, and reducing the likelihood of embedded diamond domain formation; and   said shield having one, and only one, domain along whichever edge of said shield is coplanar with said ABS; and   all domain orientations within said shield being consistently repeatable each time said shield is exposed to an initialization field.   
   
   
       22 . The magnetic shield described in  claim 21  wherein said shape is a trapezoid, one of whose parallel edges is coplanar with the ABS and wherein both said trapezoid's non-parallel edges converge towards the ABS. 
   
   
       23 . The magnetic shield described in  claim 22  wherein angles between said parallel and non-parallel edges range from −60 to +60 degrees and said trapezoid has a mean width to height ratio of between about 0.5 and 10. 
   
   
       24 . The magnetic shield described in  claim 21  wherein said shape is a trapezoid, one of whose parallel edges is coplanar with the ABS and wherein both said trapezoid's non-parallel edges diverge away from the ABS. 
   
   
       25 . The magnetic shield described in  claim 24  wherein angles between said parallel and non-parallel edges range from −60 to +60 degrees and said trapezoid has a mean width to height ratio of between about 0.5 and 10. 
   
   
       26 . The magnetic shield described in  claim 21  wherein said shape is a modified trapezoid having a first edge that is coplanar with the ABS over said first edge's entire length, second and third edges that are not parallel to one another and that are connected to said first edge, a fourth edge comprising a central part that is parallel to said first edge, and a pair of opposing outer parts, each outer part further comprising a first sub-part that extends away from said first edge and a second sub-part that connects said first part to said second or said third edge, whichever is closest. 
   
   
       27 . The magnetic shield described in  claim 26  wherein each of said outer parts has a maximum separation from said first edge that is at least 1.02 times said central part's distance from said first edge. 
   
   
       28 . The magnetic shield described in  claim 21  wherein said shape is a modified trapezoid having a first edge that is coplanar with the ABS over its entire length, two second opposing edges that are not parallel to one another and that are connected to said first edge, and a third edge comprising a central part, parallel to said first edge, connected to a pair of opposing outer parts, that are parallel to said first edge and further therefrom than said central part, each of said outer parts being connected to one of said second edges. 
   
   
       29 . The magnetic shield described in  claim 28  wherein each of said outer parts is at a maximum distance from said first edge that is at least 1.02 times said central part's distance from said first edge. 
   
   
       30 . The magnetic shield described in  claim 21  wherein said shape is a modified trapezoid having a first edge that is coplanar with the ABS over its entire length, two second opposing edges that are not parallel to one another and that are connected to said first edge, and a curved edge whose end points each connect to one of said second edges, said curved edge having a center point whose distance to said first edge is less than either of said end point's distance to said first edge. 
   
   
       31 . The magnetic shield described in  claim 30  wherein each of said end points has a maximum distance from said first edge that is at least 1.02 times said center point's distance from said first edge. 
   
   
       32 . The magnetic shield described in  claim 21  wherein said shape is a trapezoid, having a first edge that is coplanar with the ABS, a second edge parallel to said first edge, and a pair of secondary shields having edges that are parallel to, and coplanar with, said second edge, separated therefrom by no more than the shield's height, whereby said secondary shields serve to assist nucleation of domains in said magnetic shield. 
   
   
       33 . The magnetic shield described in  claim 21  wherein said shape is a hexagon having a first edge that is coplanar with the ABS, a second edge parallel to said first edge, a pair of opposing third edges connected to opposing ends of said first edge, and a pair of opposing fourth edges that connect said opposing ends of said second edges to said third edges. 
   
   
       34 . The magnetic shield described in  claim 33  wherein said hexagon has a width to height ratio of between about 0.25 and 5. 
   
   
       35 . The magnetic shield described in  claim 21  wherein said shape is an irregular octagon having a first edge that is coplanar with the ABS, a second edge, longer than and parallel to, said first edge, a pair of opposing third edges, normal to said ABS, connected to opposing ends of said first edge, and a pair of opposing fourth edges, normal to said ABS, connected to opposing ends of said second edge, and a pair of fifth opposing edges that connect said second and fourth edges. 
   
   
       36 . The magnetic shield described in  claim 35  wherein separation between said fourth edges is between about 0.25 to 5 times separation between said first and second edges. 
   
   
       37 . The magnetic shield described in  claim 21  wherein said shape is an irregular hexagon having a first edge that is coplanar with the ABS and that has a first width, a second edge, longer than and parallel to, said first edge and having a second width, a pair of opposing third edges, normal to said second edge, connected to opposing ends of said second edge, and a pair of fourth opposing edges that connect third edges to opposing ends of said first edge. 
   
   
       38 . The magnetic shield described in  claim 37  further comprising opposing edge cut features inserted between said first and fourth edges whereby said first width is reduced relative to said second width. 
   
   
       39 . The magnetic shield described in  claim 21  wherein said shape is a notched quadrilateral having a pair of parallel first edges, one of which is coplanar with the ABS, and a pair of second edges, separated by a distance and connecting said first edges to each other, each second edge further comprising multiple collinear sub-edges connected through an odd number of inwardly facing V-shaped notches, both second edges having the same number of notches and no notch having a depth that exceeds 10% of said distance between said second edges. 
   
   
       40 . The magnetic shield described in  claim 21  wherein said shape is a trapezoid modified so that one of its parallel edges further comprises a central section that is coplanar with the ABS and that is shorter than its opposing parallel edge and a pair of outer sections that connect said central section to said trapezoid's non-parallel edges, said outer sections being further from said ABS than said central section.