Unshielded spin-valve sensors exchange-biased by thin TbCo layers

Unshielded spin-valve sensors were fabricated with trackwidth W varying from 25 to 2 micron and height h ranging from 7 to 1 micron. Magnetoresistance signals range from 7.5% to 3%. We find that heads with a geometry W/h/spl ges/4 are Barkhausen noise free. The effect of current density on sensor heating and output linearization is described. The pinned NiFe layer is exchange-biased to a 120 /spl Aring/ thick TbCo layer, where the exchange field can be tuned by changing the TbCo thickness.>