公开(公告)号：SG78387A1

公开(公告)日：2001-02-20

申请号：SG1999004216

申请日：1999-08-30

Applicant: IBM

Inventor： HARDAYAL SINGH GILL ,  DOUGLAS JOHNSON WERNER

IPC: G01R33/09 ,  G11B5/02 ,  G11B5/31 ,  G11B5/39 ,  H01F10/32

Abstract: A magnetic tunnel junction (MTJ) device for use as a magnetic field sensor in a magnetic disk drive or as a memory cell in a magnetic random access (MRAM) array has an antiferromagnetic (AFM) layer formed of electrically insulating antiferromagnetic material. The magnetic tunnel junction in the sensor is formed on a first shield, which also serves as an electrical lead, and is made up of a stack of layers forming an MTJ sensor stripe. The layers in the stack are an AFM layer, a pinned ferromagnetic layer exchange biased with the AFM layer so that its magnetic moment cannot rotate in the presence of an applied magnetic field, a free ferromagnetic layer whose magnetic moment is free to rotate in the presence of an applied magnetic field, and an insulating tunnel barrier layer disposed between the pinned layer and the free layer. The MTJ sensor stripe is generally rectangularly shaped with parallel side edges and a back edge and a front edge at the air bearing surface (ABS). The pinned layer extends away from the ABS beyond the back edge of the AFM layer to contact the first shield providing a path for sensing current to bypass the electrically insulating AFM layer and flow to the tunnel junction layer. A layer of electrically insulating material isolates the pinned layer and the first shield from the second shield which also serves as an electrical lead for the MTJ sensor.

公开(公告)号：SG79217A1

公开(公告)日：2001-03-20

申请号：SG1997002735

申请日：1997-07-31

Applicant: IBM

Inventor： HARDAYAL SINGH GILL ,  BRUCE A GURNEY ,  JOSEPH FRANCIS SMYTH ,  VIRGIL SIMON SPERIOSU ,  DOUGLAS JOHNSON WERNER

IPC: G11B5/00 ,  G11B5/012 ,  G11B5/39

Abstract: An orthogonal spin valve read head is provided wherein a spin valve sensor is asymmetrically located between first and second shield layers so that image currents in the first and second shield layers produce a resultant image field which partially or completely counterbalances a stiffening field from antiferromagnetic, pinned and spacer layers in the MR sensor when sense current is conducted therethrough. Accordingly, the spin valve sensor may be located a greater distance from the second shield layer by providing a mid-gap layer between the spin valve sensor and a second gap layer. In one example, the total thickness of the mid-gap and second gap layer is four times as thick as the first gap layer which results in the image fields from the first and second shield layers completely counterbalancing the field from the antiferromagnetic, pinned and spacer layers due to the sense current.