As-deposited crystalline barium ferrite thin film media for longitudinal recording

Abstract

Using facing target sputtering, crystalline barium ferrite (BaFe 12O 19, BaM) has been deposited onto a silicon nitride coated carbon substrate, producing high-quality, randomly oriented crystalline films in-situ at a substrate temperature of 640°C without post-deposition annealing. Using inductive read-write heads, longitudinal recording tests reveal that randomly oriented BaM thin films have a linear recording density ( D 50) greater than 100 kfci and a high signal to noise ratio (∼39 dB). The low noise performance of BaM thin film is consistent with its measured small and negative ΔM value, indicating no intergranular exchange interaction. It is argued that BaM is intrinsically a low-noise medium with exchange decoupled grains, regardless of how the grains are oriented and how dense the sputtered films are.