Patent ID: 8259420

Claim:
A magnetoresistive element in a magnetic device, comprising: (a) a pinned layer formed on a substrate; (b) a non-magnetic spacer with a first surface contacting the pinned layer and a second surface opposite the first surface wherein both first and second surfaces are parallel to the substrate; and (c) a composite free layer contacting the second surface of the non-magnetic spacer; said composite free layer is comprised of: (1) a first ferromagnetic layer including one or more of CO W Fe (100-W) , [CO W Fe (100-W) ] (100-Y) B Y where w is from 0 to about 100% and y is from 10 atomic % to about 40 atomic %, and an alloy of one of the aforementioned compositions comprised of one or more additional elements including Ni, Ta, Mn, Ti, W, Zr, Hf, Tb, and Nb, said first ferromagnetic layer has a positive magnetostriction, an inner surface contacting the second surface of the non-magnetic spacer, and an outer surface opposite the inner surface that has one or both of a modified structure and increased surface energy with respect to other portions of the first ferromagnetic layer; (2) an insertion layer with a first side contacting the outer surface of the first ferromagnetic layer, and a second side contacting a second ferromagnetic layer, said insertion layer includes at least one magnetic element selected from Fe, Co, and Ni and at least one non-magnetic element selected from Ta, Ti, W, Zr, Hf, Nb, Mo, V, Mg, or Cr; and (3) the second ferromagnetic layer comprised of one or more of CO W Fe (100-W) where w is from 0 to about 100 atomic %, Ni Z Fe (100-Z) where z is from about 70% to 100%, and an alloy wherein CoFe or NiFe are combined with one or more elements selected from Ni, Ta, Mn, Ti, W, Zr, Hf, Tb, Nb, and B, said second ferromagnetic layer has a negative magnetostriction or a small positive magnetostriction (λ) so that overall λ for the composite free layer is less than about 5×10 −6 .