Bulk and boundary effects on the decay of the thermodynamic Casimir force

TL;DR

This paper analyzes how boundary conditions and phase symmetry influence the decay of the thermodynamic Casimir force in finite correlation length phases, using two-dimensional field theory and discussing extensions to higher dimensions.

Contribution

It provides an exact analysis of boundary condition effects on Casimir force decay in 2D field theory, highlighting differences between symmetry-preserving and breaking conditions.

Findings

Decay depends on boundary symmetry properties

Symmetry breaking alters the force decay behavior

Features of bulk universality class can modify decay patterns

Abstract

We consider the decay of the thermodynamic Casimir force in phases with a finite correlation length. For the case of the strip, we use properties of low energy two-dimensional field theory to show that the decay depends on the symmetry properties of the boundary conditions, in distinctive ways that we determine exactly. Features characteristic of the bulk universality class may induce modifications that we also discuss. Symmetry breaking and symmetry preserving boundary conditions exchange their role with respect to the decay of the force when exchanging spontaneously broken with disordered phases. Several of our arguments extend to higher dimensions.