Magnetic Switching Behavior of Granular Perpendicular Magnetic Media With Different Lateral and Vertical Exchange Coupling

The magnetic switching behavior was measured for granular oxide media containing an exchange control layer (ECL). Investigations of the switching behavior show that the initial minor loop slope represents the degree of incoherent switching in the film. Multilayered granular oxide media with different inter-granular coupling in both lateral and vertical directions, is prepared by varying the oxide grain isolation and ECL thickness. The switching behavior of well isolated oxide grains strongly depends on the thermal stability of the switching segments through the ECL layer. The oxide grains with higher thermal stability vertically decouple at thinner ECL, resulting in a stronger incoherency of switching. In addition, the increase of lateral exchange coupling between oxide grains reduces the vertical decoupling at given ECL condition. For media with a smaller cluster size, the ECL magnetization and thickness has a more pronounced effect on the switching, indicating that fabrication of well isolated grains is important to optimize the media switching mode.