Remanence and longitudinal recording properties of advanced particulate media and metal thin-film media

A comparison is made of the magnetic remanence and longitudinal recording properties of advanced particulate media with metal thin-film media. The remanence properties were studied parallel and orthogonal to the track direction and were diagnostic of recording performance. The recording properties were measured using thin-film heads with inductive-write and magnetoresistive-read elements. Longitudinal barium ferrite and isotropic cobalt alloy media show substantially narrower switching field distributions (SFDs) compared to acicular cobalt-modified γ-Fe₂O₃ media. Narrow SFD, high H_c, and small M_rδ lead to small, well-defined magnetic transitions and high bit densities. Indeed, there is a linear correlation between the calculated transition length, a, and the linear density. Results confirm that particulate barium ferrite and cobalt alloy media have very small transition lengths and high linear densities. Cobalt-modified γ-Fe ₂O₃ media show lower linear densities; however, their intrinsic signal-to-noise ratios (SNR) are much higher compared to the barium ferrite and cobalt alloy media. The trend of noise with increasing density or frequency differs for the three types of media