When is Short-Range ``Critical'' Wetting Not Critical?

Abstract

Recent interface Hamiltonian studies have posed the question: Can an instability mechanism, due to a variable interface stiffness, drive bare critical wetting transitions first order? We argue ``yes'' on the basis of a novel nonlinear renormalization group study allowing semiquantitative analysis in dimensions $1<d\ensuremath{\le}3$. Fluctuation-induced first-order wetting occurs for $d\ensuremath{\gtrsim}2.41$ if the wetting parameter $\ensuremath{\omega}(T)$ is less than a tricritical value ${\ensuremath{\omega}}_{t}(T)$. Crucially, in $d\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3$ (for relevant temperatures) we find ${\ensuremath{\omega}}_{t}\ensuremath{\gg}\ensuremath{\omega}$ clearly enhancing first-order wetting as compared with earlier less conclusive studies.