Patent ID: 8107201

Claim:
A hard bias structure for providing a longitudinal bias to a free layer in a spin valve within a magnetic read head, comprising: (a) a first composite hard bias layer formed on a substrate and on either side of a spin valve, comprising: (1) a first hard bias layer with a first thickness, a coercivity (Hc), a top surface, and an Mrt value; and (2) a second hard bias layer formed on the top surface of the first hard bias layer, said second hard bias layer has a second thickness greater than said first thickness, an Mrt value, and a coercivity greater than that of the first hard bias layer; and (b) a second composite hard bias layer formed on said first composite hard bias layer, comprising: (1) a third hard bias layer with a top surface, and a first thickness, coercivity, and Mrt value essentially the same as that of the first hard bias layer; and (2) a fourth hard bias layer formed on the top surface of the third hard bias layer, said fourth hard bias layer has a thickness, coercivity, and Mrt value essentially the same as that of the second hard bias layer; wherein at least one of the first, second, third, or fourth hard bias layers contacts said free layer in the spin valve.