In this study, we show that high frequency reversal of magnetization for over Tbits/in.2 recording density can be controlled by adjusting the magnetic field, media properties, and bit geometry. Using micromagnetic simulation, magnetization reversal speed depends strongly on exchange coupling (A) and the ratio between applied and anisotropy fields. The analysis also shows the effect of anisotropy variation and interbit interaction on magnetization switching. When high frequency write field is applied to less than a half bit, the switching may not occur for A higher than an optimal value. This characteristic can be used to reduce overwriting on adjacent bits.