Patent ID: 8507113

Claim:
A magnetic sensor stack body comprising, on sides of opposed junction wall surfaces of a magnetoresistive element disposed on a substrate, field regions for applying a bias magnetic field to the element, wherein the field region includes first and second magnetic layers having magnetic particles having crystal c-axes, the first magnetic layer is disposed adjacent to the junction wall surface in the field region, the crystal c-axes in the first magnetic layer are aligned and oriented along an ABS in a film plane, the second magnetic layer is disposed adjacent to the first magnetic layer in the field region, the crystal c-axes direction in the second magnetic layer are distributed at random in a plane, the first magnetic layer is made of Co—Pt, Co—Cr—Pt, crystal structure (hcp) selected Cr—Pt, or Fe—Pt, Co—Pt, or an alloy thereof, the second magnetic layer is made of Co—Pt, Co—Cr—Pt, or an alloy thereof, an underlayer made of Cr, Cr—Mo, Cr—Ti, Nb, Ta, W or an alloy thereof having a body-centered cubic crystal structure (bcc) of them is provided on the field region and the junction wall surface, the underlayer has a thickness which is 3 to 8 nm in the field region and is less than 3 nm in the junction wall surface, the underlayer has a (110) lattice plane in the field region and is in an amorphous state in which no (110) lattice plane is formed in the junction wall surface, and the first magnetic layer is formed on the underlayer and has a cross-sectional shape, on a surface parallel to the ABS, of an approximate parallelogram formed by a pair of sides along the junction wall surface and a pair of sides along a face of the substrate in a region adjacent to the junction wall surface.