Nature of phase transition(s) in striped phase of triangular-lattice Ising antiferromagnet

TL;DR

This paper investigates the phase transition mechanisms in the striped phase of a triangular-lattice Ising antiferromagnet, highlighting the role of domain walls and the conditions for different types of phase transitions.

Contribution

It analyzes fluctuation-induced disordering scenarios and identifies the dominant first-order transition mechanism involving domain wall networks.

Findings

Disordering occurs via a first-order phase transition involving domain walls.

A possible continuous transition involves double domain walls but requires specific coupling conditions.

The dominant disordering mechanism is related to zero modes in the domain wall network.

Abstract

Different scenarios of the fluctuation-induced disordering of the striped phase which is formed at low temperatures in the triangular-lattice Ising model with the antiferromagnetic interaction of nearest and next-to-nearest neighbors are analyzed and compared. The dominant mechanism of the disordering is related to the formation of a network of domain walls, which is characterized by an extensive number of zero modes and has to appear via the first-order phase transition. In principle, this first-order transition can be preceded by a continuous one, related to the spontaneous formation of double domain walls and a partial restoration of the broken symmetry, but the realization of such a scenario requires the fulfillment of rather special relations between the coupling constants.