Spontaneous symmetry breaking of domain walls in phase-competing regions

TL;DR

This paper investigates how domain walls in systems with two competing Ising-type orders undergo a spontaneous symmetry breaking, revealing a second-order phase transition detectable via susceptibility divergence.

Contribution

It demonstrates that domain walls exhibit a second-order phase transition related to the secondary order parameter, modeled by a Landau theory in a two-component $$ theory.

Findings

Domain walls show a second-order phase transition.

The phase boundary differs from the spinodal line.

Susceptibility diverges at the transition.

Abstract

We study the nature of domain walls in an ordered phase in the phase-competing region of two Ising-type order parameters. Considering a two-component $\phi^4$ theory, we show that the domain wall of the ground-state (primary) order parameter shows a second-order phase transition associated with the secondary order parameter of the competing phase; the effective theory of the phase transition is given by the Landau theory of Ising-type phase transition. We find that the phase boundary of this phase transition is different from the spinodal line of the competing order. Experimentally, the phase transition is detected by the divergence of the susceptibility corresponding to the secondary order when the temperature is quenched to introduce the domain walls.