Spin-valve heads for 20 Gbit/inch(2) recording

Spin-valve (SV) heads with antiferromagnetic control layers for 20 Gbit/inc h(2) recording were designed by solving the Landau-Lifshitz-Gilbert equatio n. The calculated SV-head model has a read track width of 500 nm and a dete cted minimum bit length of about 50 nm recorded on a medium whose thickness , t(mag), is 14 nm, and the product of remanent nux density, B-t, and thick ness, t(mag), is 50G mu m. The head-to-medium spacing is 30 nm. When the se nsing-current density is less than about 5.0 x 10(7)A/cm(2), the thickness of the pinning layer and the free layer is appropriate to be 2.0 nm and 3.0 nm, respectively The resolution, V-high/ V-low, is about 0.67 when the opt imum shield gap length, G, is 80 nm. The resolution depends on the sensing- current density, J, as well as the gap length G. We obtained a low-density output voltage of 700 mu V-p.p, which is practically applicable, by selecti ng the optimum element size.