Magnetization Reversal Dynamics Many important technological applications involvereversing magnetic moment in a magnetic materialwithin a very short time period. For instance, incomputer hard-disk drives, storing a single bit re-quires reversing the magnetic moments of both thewrite transducer and the thin film recording mediumin a fraction of a nanosecond. Understanding mag-netization reversal dynamics is critical in theseapplications (Bertram and Zhu 1992, Mao 2000,Zhu 2001, Zhu and Zheng 2002). In general, magnetization reversal in a magnetic material, either of a bulk or thin film, or a particulateform, is always complex. For studying the reversaldynamics, there are many experimental means, in-cluding time-resolved Kerr microscopy field in situtransmission electron microscopy, field in situ scan-ning electron microscopy with polarization analysis(SEMPA), and field in situ magnetic force microscopy(Hubert and Sch .afer 2000).