Study of magnetic and recording properties of dc magnetron sputtered CoCr thin films

CoCr thin films were prepared by dc magnetron sputtering, on aluminum substrates in a dual-sided sputtering system. Ouchi and Iwasaki [J. Appl. Phys. 57, 4013 (1985)] have reported that for magnetron sputtered CoCr thin films on a substrate at constant temperature, the coercivity is dependent on the substrate temperature and not on the deposition rate. However, for applications in which no heat sinking is applied during deposition the temperature of the film and the substrate increases with time which produces a film with a coercivity gradient that affects both the magnetic and the recording properties. This report investigates the effects of this coercivity gradient on the recorded output amplitudes. The average perpendicular coercivity Hc(⊥) was observed to increase from 65 to 440 Oe, and then decrease with further increase in thickness. The average dispersion of the c axis, Δθ50, decreased from 6.5°, for the thin films, to 2.8° for the thick films. Coercivity measurements reveal a relatively soft film [Hc(⊥)