Physics Seminar

**Talk by Dr. Joseph Indekeu**

KU Leuven, Belgium

We consider a mean-field density-functional model for three-phase equilibria and wetting. The model features two densities and two control parameters, one of which is related to order parameter asymmetry or spatial anisotropy. The global wetting phase diagram in the space of these two parameters is rich. It features first-order, second-order, continuously-varying-order and infinite-order wetting transitions. The divergence of the wetting layer thickness is usually logarithmic as a function of the distance to the transition, but, in contrast, algebraic upon approach of an infinite-order transition. Further, an approximate interface potential approach is proposed, which allows us to derive analytic predictions for the singular behavior of thermodynamic functions near wetting, in accordance with accurate numerical computations. It is conjectured that previously developed mean-field models, such as, for example, one

for ferromagnets with cubic anisotropy also contain a segment of infinite-order transitions. We speculate that the possibility of varying the spatial anisotropy of the magnetic interaction in these systems might well lead the way towards the first experimental realization of infinite-order wetting. Time permitting, comments on preliminary renormalization group results will be given.

K. Koga, J.O. Indekeu, and B. Widom, “Wetting transitions of continuously varying or infinite order from a mean-field

density-functional theory.” Molecular Physics 109, 1297 (2011)

K. Koga, J.O. Indekeu, and B. Widom, “Infinite-Order Transitions in Density-Functional Models of Wetting”. Phys. Rev. Lett. 104, 036101 (2010)