Microscopic cut-off dependence of an entropic force in interface propagation of stochastic order parameter dynamics

The steady propagation of a $(d-1)$-dimensional planer interface in $d$-dimensional space is studied by analyzing mesoscopic non-conserved order parameter dynamics with two local minima under the influence of thermal noise. In this analysis, an entropic force generating interface propagation is formulated using a perturbation method. It is found that the entropic force singularly depends on an ultraviolet cut-off when $d \ge 2$. The theoretical calculation is confirmed by numerical simulations with $d=2$. The result means that an experimental measurement of the entropic force provides an estimation of the microscopic cut-off of the mesoscopic description.