Declan Macken

Rapid thermal processing of sendust for magnetic recording applications

This article describes a method of thermally processing sputter deposited 2-μm-thick sendust films to produce the high permeability form of this alloy. The method described utilizes rapid thermal processing to induce the phase change in the sendust from the disordered α type to the DO3 ordered structure as confirmed by Mossbauer spectroscopy. Optimization of the treatment resulted in films with a coercivity of less than 0.4 Oe. At a treatment temperature of 500 °C, a soak time of 120 s was required to achieve optimum coercivity and at a temperature of 600 °C a time of 15 s was required. Treatments at the lower end of the temperature range with longer process times gave a greater degree of reproducibility in the coercivity results. This thermal treatment gives rise to several performance advantages of the material relative to untreated sendust, including reduced “out-of-plane” magnetic component, improved high frequency permeability, and surface passivation. In addition, the processing times associated wit...