Nonuniform thermal reversal in single-domain patterned media

Patterned media shows great potential for future ultrahigh-density magnetic recording. The thermal stability is determined by the relevant transition states. We apply the nudged elastic band method to calculate energy barriers and thermal reversal modes as a function of the island size and intergrain exchange coupling. Nonuniform reversal modes and transition states are found even in single-domain islands. The resulting energy barriers are significantly lower than those estimated from simplified reversal modes.