Coupling of interfacial and spin-like coordinates in effective Hamiltonians for complete and critical wetting

Abstract

In this paper the effects of including position-dependent stiffness coefficients in the coupled effective Hamiltonian models appropriate for both complete and critical wetting are considered. This analysis is motivated by a nonlinear functional renormalization group approach applied for the first time to two-field interface models, and cast in a simple matrix form. In particular we (i) determine the renormalization group flow of the capillary parameter and confirm that its renormalization at complete wetting is preserved at all orders and (ii) demonstrate that the stiffness instability mechanism is robust, and indeed strengthened, under the inclusion of coupling terms near critical wetting.