Patent ID: 8289663

Claim:
An ultra-low RA (resistance x area) sensor, comprising: (a) a stack of layers comprised of a seed layer, anti-ferromagnetic (AFM) layer, and a synthetic anti-ferromagnetic (SyAF) pinned layer having an AP2/coupling/AP1 configuration wherein the AP1 layer is comprised of a CoFe, CoFeB, CoB, FeB, or CoFeX layer wherein X=Ni, Cu, Mo, Cr, Zr, said AP1 layer contacts a composite spacer and said stack of layers is sequentially formed on a substrate; (b) the composite spacer consists of one metal (M) layer and one low band gap insulating layer or semiconductor material layer (B) formed on the AP1 layer in a B/M, or M/B configuration; (c) a free layer formed on the composite spacer; and (d) a capping layer on the free layer.