FeTaN/IrMn exchange-coupled multilayer films as soft underlayers for perpendicular media

Soft underlayers of FeTaN/IrMn exchange-coupled films for perpendicular media have been investigated. FeTaN(t_FeTaN)/IrMn (10 nm) multilayer films having different FeTaN thicknesses t_FeTaN from 20 nm to 200 nm were prepared while keeping the total FeTaN thickness at 200 nm. When t_FeTnN decreased below 100 nm to 20 mn, the exchange bias field increased from 3.6 Oe to 77 Oe, and the pinning field from 25 Oe to 105 Oe. The interfacial exchange energy, J, was 0.10~0.13 ergs/cm². As the exchange bias field increased, the angular reversibility increased from 10° to 57° in good agreement with the coherent rotational model. Radially oriented multilayer films of FeTaN (20 nm)/[IrMn(10 nm)/FeTaN(20 nm)]₉ were successfully prepared on 65 mm disks and showed excellent angular reversibility, a pinning field >70 Oe, and a permeability of 70 up to 2 GHz