Microstructural dependence of magnetization process in thin film recording media

The magnetization process in thin film recording media is studied by utilizing numerical micromagnetics. The Landau-Lifshitz or Giibert equation is solved, where the total system energy provides the driving torque for the evolution of each grain's magnetization. The principles, algorithms, and implementation of micromagnetic simulation are presented in detail.; The intergranular interactions can be described by magnetostatic and exchange coupling constants scaled by medium intrinsic crystalline anisotropy energy constant. An analytical model of high field torque analysis is developed to aid the experimental determination of medium intrinsic anisotropy energy constant. Coupled with experimental measurement, numerical micromagnetic simulation is applied to the characterization of current CoCrPt disk media with bicrystal microstructure. A tight coupling approximation is proposed to relate the bicrystal microstructure to the dispersion of an effective anisotropy magnitude. The recording performance of candidate media for future ultrahigh density magnetic recording is evaluated. The microstructural dependence of replay signals, medium nonlinearities, and track edge recording are studied by recording simulation in longitudinal thin film media with a small track width.; The dynamic magnetization reversal process is numerically studied by numerical micromagnetics. Medium magnetization switching processes under a uniform reverse field and a record head field are examined. The gyromagnetic switching speed in longitudinal and perpendicular media are compared. Magnetization reversal dynamics with a finite recording track width is examined in detail by including the head field rise time. The gyromagnetic switching limit on medium data rate is investigated for media with various Gilbert damping constants and record head field rise times.