WEAR OF THE MAGNETIC HEAD CARBON OVERCOATED DISK INTERFACE - A RAMAN-SPECTROSCOPY STUDY

Raman spectroscopy was applied in the wear track region of carbon over coated magnetic storage disks after drag and contact start/stop (CSS) tests with a manganese-zinc ferrite slider. The ratio of the relative intensities of the two major carbon bands, one centred near 1360 cm-1 (the D band) and the other centred between 1560 cm-1 and 1580 cm-1 (th e G band) increased with the number of cycles in the drag test and fir st increased and then decreased in the CSS test. The changed D/G spect ral intensity ratio is attributed to temperature changes. Raman spectr a of carbon layers sputtered to different thicknesses between 15 nm an d 30 nm were essentially identical, indicating uniformity in overcoat composition. Raman spectra are consistent with generally higher temper atures in CSS tests than in drag tests. The intensity of a Raman band centred at 625 cm-1 increased with number of drag cycles in the slider spectrum. Its frequency and shape corresponds to that reported for ma nganese ferrite in the literature. Its intensity increase with wear re mains to be explained. Laser irradiation of carbon overcoats in a Rama n spectrometer can contribute to changes of the carbon structure by he ating.