Patent ID: 7505235

Claim:
A method for controlling magnetostriction in a free layer of a magnetic memory device, comprising: forming a pinned layer; forming a separation layer over the pinned layer; and forming a bilayer, composite free layer, the forming the bilayer, composite free layer includes: forming a first free layer, the first free layer comprising a CoFe alloy; and forming a second free layer, the second free layer comprising a NiFe alloy, wherein the forming the first free layer of CoFe alloy and the forming of the second free layer of NiFe alloy further comprises forming the first free layer of CoFe alloy with a predetermined first thickness and forming the second free layer of NiFe with a predetermined second thickness, wherein the ratio of the predetermined first thickness to the predetermined second thickness is selected to provide a predetermined magnetostriction and wherein at least one of the CoFe alloy and NiFe alloy includes an addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti, the ratio of the first thickness and second thickness being selected to provide a desired magnetostriction and the addition of at least one element of B, P, Si, Nb, Zr, Hf, Ta and Ti being controlled to maintain a substantially constant sensor resistance while adjusting the ratio of the first thickness and second thickness to provide a desired magnetostriction.