A Landau theory is studied for wetting and interfacial depinning in systems with internal defect planes, which can model grain boundaries. The defect plane divides the infinite system into two semi-infinite ones, each of which can undergo phase transitions of the wetting type. If both semi-infinite systems have the same critical temperature Tc, critical-point wetting does not occur unless the defect plane remains ordered at Tc. If the two semi-infinite systems have unequal critical temperatures, Tc- and Tc+, the phenomena are similar to those of wetting at a free surface or wall, and critical-point wetting is the rule. In the limit that Tc- and Tc+ approach each other, the line of tricritical wetting connects to the surface of defect-plane criticality and becomes the line of surface-bulk multicriticality of the defect plane. Implications for similar phenomena beyond Landau theory (e.g., in the Ising model) are outlined.
ASJC Scopus subject areas
- Condensed Matter Physics