Interface localization near criticality

TL;DR

This paper develops a first-principles theory of interface localization near critical points, revealing conditions for wetting transitions and their critical behavior in planar systems at phase coexistence.

Contribution

It provides a theoretical framework for understanding interface delocalization and wetting transitions near criticality, including boundary effects and critical exponents.

Findings

Mutual delocalization occurs when the correlation length exponent $ u$ ≥ 1.

Boundary delocalization is a continuous transition with specific critical exponents.

Interaction with boundaries introduces additional scales affecting localization strength.

Abstract

The theory of interface localization in near-critical planar systems at phase coexistence is formulated from first principles. We show that mutual delocalization of two interfaces, amounting to interfacial wetting, occurs when the bulk correlation length critical exponent $\nu$ is larger than or equal to 1. Interaction with a boundary or defect line involves an additional scale and a dependence of the localization strength on the distance from criticality. The implications are particularly rich in the boundary case, where delocalization proceeds through different renormalization patterns sharing the feature that the boundary field becomes irrelevant in the delocalized regime. The boundary delocalization (wetting) transition is shown to be continuous, with surface specific heat and layer thickness exponents which can take values that we determine.