Maximization of the output of shielded current perpendicular to the plane spin valve heads by optimum sense current and hard bias

The head efficiency of shielded current perpendicular to the plane (CPP) spin valve heads of 20 and 200 Gbpsi dimension has been computed and analyzed by an analytical approach utilizing the transmission line model (TLM), and a numerical approach using micro magnetic simulation. For the TLM, the effect of the circular current field was taken into account by incorporating the distribution of the effective permeability of the free layer. Both results showed higher head efficiency for the configuration where sense current field cancels the hard bias field at the front side (air-bearing side) of the free layer. The difference of efficiency by sense current direction was significant at higher sensor height and stronger hard bias. The effect was also observed experimentally on transfer curves from CPP spin valve heads of 20 Gbpsi dimension. (C) 2002 American Institute of Physics.