CoFe/IrMn exchange-coupled soft underlayers for perpendicular-media

Summary form only given. It is widely recognized that the soft underlayers used to optimize the performance of perpendicular recording media can give rise to additional media noise due to domain wall instabilities in the underlayer. The attractive characteristics for underlayers of high magnetization FeTaN/IrMn exchange coupled multilayers exhibiting only a single remanent direction has recently been demonstrated. However, to maintain a total ferromagnetic thickness of 200 mn and simultaneously achieve sufficient exchange coupling to reduce the permeability to /spl sim/100, 19 layers were required. Here the replacement of FeTaN by CoFe which also has a high saturation magnetization (18 /spl sim/ 24 kG) but a significantly higher anisotropy field (27 Oe vs. 9 Oe in a 50 mn thickness) is described which allows the number of layers to be reduced from 19 to 7.