Interfacial Roughening in Field Theory
Prof. Dr. Gernot Münster (Universität Münster)

Many systems of statistical physics can develop interfaces, separating different phases or substances. These include Bloch walls in ferromagnets, binary liquid mixtures, liquid-gas systems and systems of immiscible polymers. The profile of an interface determines several other properties such as the interface width and interface tension and therefore plays a central role for the physics of interfaces. Long-wavelength capillary wave fluctuations lead to the roughening phenomenon. It implies a broadening of the interface such that in a three-dimensional system the width of an interface depends logarithmically on the system size and diverges in the limit of an infinite system. This phenomenon is commonly described in terms of the capillary wave model, which deals with fluctuating, infinitely thin membranes, requiring ad hoc cut-offs in momentum space. We investigate the interface roughening in the framework of statistical field theory. The interface profile and width are calculated analytically, resulting in finite expressions with definite coefficients, which are valid in the scaling region.