Low Noise Recording Medium Design with Co-Cr-Nb Film

Abstract

Abstract---A low noise medium design is described focussing on Co-Cr-Nb films. Targeted magnetic parameters for a low noise medium (Ms -200 emu/cm 3 , Hcl. > 2500 De, Hc/Hkl. > 1/3) are presumed by considering M-H loops ofCo-Cr films. Only Co-CrNb films with high Cr contents could satisfy these parameters when deposited with a substrate temperature of 600 "C. The high deposition temperature was adopted according to the elevated transition temperature of about 500 "C at which Cr microsegregation in the film becomes enhanced. Magnetic properties of the film was also supported by a highly oriented Ti underlayer. In the crystallographic point of view, a Co-Cr-Nb film was found to have a more continuous structure in the film thickness direction than a Co-CrTa film.

Overview of latest work on perpendicular recording media

“…Potentiodynamic polarization measurement studies of the films suggested that Nb addition enhanced Cr microsegregation in the film. Although the obtained Co-Cr-Nb perpendicular recording media showed a low noise property [10], the recording performance was not as high as expected. The recording property of the media was improved by further addition of Pt which increased the loop slope about 1.5 times larger [7].…”

“…A large of around 0.8 with a small of about one for perpendicular M-H loop was obtained by adding a small amount of Nb to Co-Cr [10], as shown in Fig. 9.…”

Strategy for Implementation of Perpendicular Magnetic Recording

“…Such media exist at present except for the needed noise properties. The development of low noise media is in progress now [22], [23]. The large Ms•o of the media would expand the application of AMR heads.…”