Coherent and incoherent magnetization reversal in single and multi-layered films for magnetic recording with out-of-plane anisotropy

The magnetization reversal in three samples for magnetic recording, which display a strong out-of-plane anisotropy, has been studied by means of quantitative magneto-optic Kerr vector magnetometry. Two samples are single layer, one is a CoNiO thin film and the other is a CoCr film. The third sample is composed of three CoNiO layers. The results indicate that the magnetization of the two CoNiO samples undergoes a macroscopically coherent rotation out-of-plane, without domain formation, until the external field reverses and reaches a critical value, at which a macroscopically incoherent magnetization reversal takes place. The higher critical field value is displayed by the CoNiO trilayer. In the case of CoCr, the critical field has an opposite sign compared to the CoNiO structures and the incoherent reversal takes place over a much wider field values interval.