Study of intergranular exchange coupling in longitudinal CoCrPt and perpendicular CoNi/Pt thin films for magnetic recording

Abstract

We investigated magnetic intergranular coupling in both longitudinal and perpendicular media, suitable for high-density recording. The longitudinal media were two kinds of CoCrPt thin films with one strongly and the other weakly coupled. The perpendicular media were two kinds of CoNi/Pt multilayered thin films with one strongly and the other weakly coupled. The dc saturated and demagnetized magnetic states of thin films were studied by magnetic force microscopy. The demagnetized state of strongly coupled media shows greater contrast than that of granular ones for both CoNi/Pt and CoCrPt. In the dc saturated states, CoNi/Pt shows uniform distribution of the magnetization, while CoCrPt shows distinct remanent magnetization, which is smaller than saturation magnetization. A recording demonstration shows that the perpendicular medium is advantageous over the longitudinal one, and the weakly coupled medium outweighs the strongly coupled one for high-density recording.