Magnetization reversal in sputtered Co-Cr films

The magnetic characteristics of a set of r.f. sputtered Co-Cr films of various composition and thickness are examined in order to evaluate their performance for perpendicular recording. The mechanism of the magnetization reversal is discussed on the bases of: i) the shape of the rotational hysteresis loss as a function of the internal rotating field, ii) the value of the rotational hysteresis integral, iii) the dependence of the coercivity Hc, and the remanence coercivity Hr, on the angle between the easy direction and the field direction. In particular the measurements of rotational hysteresis were performed by monitoring the rate of change of the angular velocity of a top containing the specimen spinning in a magnetic field perpendicular to its axis. The deviation of the experimental behaviour from the ideal models are related to the amount of anomalies in the columnar structure of the film.