Vortex effects on domain growth: The clock model

The development of order in the clock (Z_N ) model is studied following a quench from high temperature (T≫T_c ) to very low temperatures, where the system has a ferromagnetic ground state. We find that the mean domain size R and energy E do not increase algebraically with time, in contrast to the behavior observed for the Q-state Potts model. Instead, we find that quenched-in vortices, present even at low temperature, play an important role in the domain growth, ultimately pinning the growth for long times.