High linear density written transitions in exchange isolated Pt/CoCrTa multilayer thin films

Abstract

Multilayer Pt/CoCrTa thin-film structures have been prepared which display little intergranular exchange coupling and nearly 100% remanence in the perpendicular direction. Magnetic recordings of continuous square wave patterns have been made and characterized using an inductive contact recording transducer and by magnetic force microscopy. Written transitions appear to retain good fidelity at more than 300 000 transitions per inch. With exchange isolation of the grains, media noise becomes negligible relative to thermal noise from the recording system electronics. Analysis of magnetic force microscopy images yields a signal to integrated noise ratio of 17 dB at 309 000 transitions per inch written in a 4 μm wide track, which is comparable to a measured signal to total noise ratio of 8 dB at 350 000 reversals per inch measured using an inductive transducer at 100 in./s. These results are contrasted with observations on exchange coupled Pt/Co multilayers.

Study of magnetization reversal in ultrathin magnetic multilayers using in situ MOKE

“…This is in apparent contrast to recent results we have reported from magnetic recording experiments on films with greater thickness and lower saturation magnetization. 1 The domain wall energy density w decreases with increasing cosputtered CrTa ͑as in A number of shortcomings are apparent in the model employed. The model does not consider hysteresis.…”

“…1 A recent ͑MFM͒ study has shown that equilibrium domain structures vary greatly depending on stoichiometry and deposition temperature. 2 The size of the domain is also strongly influenced by the thickness of the film.…”

Overview of latest work on perpendicular recording media

“…Reduction of medium noise in Co/Pt multilayer media [16] was also achieved by using Co-Cr-Ta instead of Co layers with an elevated substrate temperatures [17]. In this case, the reduction in the domain size is caused by the Cr microsegregation in the Co-Cr alloy layer.…”

Co/Pd multilayers for perpendicular magnetic recording media

“…Deposition parameters, such as temperature [4] and doping, e.g. B, Cr, CrTa, Al [8][9][10][11][12], have been studied for their potential to reduce domain sizes. Unfortunately, all of these techniques involve high growth temperatures and therefore larger grain sizes.…”