Quantitative Measurement of Cr Segregation in Co0.8–x Crx Pt0.1 B0.1 Recording Media by Scatter Diagram Analysis

We describe the scatter diagram analysis of chemically resolved energy-filtered transmission electron microscopy (EFTEM) images and demonstrate its application in obtaining quantitative information about the segregation of Cr on the nanometer scale. The recording performance of Co–Cr based magnetic media depends critically on the microstructure of the thin film alloy, i.e., the degree of segregation of Cr to the grain boundaries determines the extent of magnetic isolation that can be achieved. Magnetic isolation of the grains reduces transition widths and thereby allows increased recording densities. The EFTEM results obtained correlate well with both the magnetic properties and recording performance of the media, i.e., a higher Cr content of 16 at. % (compared with a 10 at. % sample) shows substantial segregation of Cr with about 8% (0.06%) of the image area, most of it at the grain boundaries, having a Cr concentration which is higher than 24 at. %, and a medium signal to noise ratio of 17.8 dB (15.3 dB).