Effect of grain size, cluster size, and crystallographic orientation upon simulation of longitudinal recording media

Simulations of hexagonal magnetic particles with uniform exchange energy and random c-axis in-plane orientation do not reproduce real media magnetic properties. Simulation software was thus modified to model four experimentally observed Co-alloy microstructures, to distinguish the effects of grain size, cluster size, exchange decoupling, and cluster substructure; and to more accurately model real media behavior. Results include: (1) Clusters of isolated uniaxial particles act like single grains having the cluster size. Exchange decoupling on a size scale smaller than the crystallographic grain size has little effect upon hysteresis loops or media noise. (2) The magnetic properties of clustered bicrystal and randomly oriented media depend on the exchange interactions within and between clusters of grains. Media hysteresis loops and recorded tracks are well simulated using exchange energies within randomly oriented or bicrystal grain clusters up to ten times larger than those used in the standard model. (C) 1997 American Institute of Physics.