Analytic approximations for the velocity of field-driven Ising interfaces

摘要

We present analytic approximations for the field. temperature. and orientation dc dependences of the interface velocity in a two-dimensional kinetic Ising model in a nonzero field. The model, which has nonconserved order parameter. is useful for ferromagnets, ferroelctrics, and other systems undergoing order-disorder phase transformations,ns driven by a bulk free-energy difference. The solid-on-solid (SOS) approximation for the microscopic surface structure is used to to estimate mean spin-class populations, from which the mean interface velocity call br obtained for ally specific single-spin-flip dynamic. This linear-response approximation remains accurate for higher temperatures than the single-step and polynuclear growth models, while it reduces to these in the appropriate low-temperature limits. The equilibrium SOS approximation is generalized by mean-field arguments to obtain field-dependent spin-class populations for moving interfaces, and thereby a nonlinear-response approximation For the velocity. The analytic results for the interface velocity and the spin-class populations are compared with Monte Carlo simulations. Excellent agreement is round in a wide range of field, temperature, and interrace orientation. [References: 41]