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

Abstract

Soft underlayers of FeTaN/IrMn exchange-coupled films for perpendicular media have been investigated. FeTaN(t/sub FeTaN/)/IrMn (10 nm) multilayer films having different FeTaN thicknesses t/sub FeTaN/ from 20 nm to 200 nm were prepared while keeping the total FeTaN thickness at 200 nm. When t/sub 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/spl sim/0.13 ergs/cm/sup 2/. As the exchange bias field increased, the angular reversibility increased from 10/spl deg/ to 57/spl deg/ in good agreement with the coherent rotational model. Radially oriented multilayer films of FeTaN (20 nm)/[IrMn(10 nm)/FeTaN(20 nm)]/sub 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.