Unshielded spin-valve sensors were fabricated with trackwidth W varyin
g from 25 to 2 micron and height h ranging from 7 to 1 micron. Magneto
resistance signals range from 7.5% to 3%. We find that heads with a ge
ometry W/h greater than or equal to 4 are Barkhausen noise free. The e
ffect of current density on sensor heating and output linearization is
described. The pinned NiFe layer is exchange-biased to a 120 Angstrom
thick TbCo layer, where the exchange field can be tuned by changing t
he TbCo thickness.