The Widom line in the Ising model on a decorated bilayer lattice

TL;DR

This paper investigates the Ising model on a decorated bilayer lattice, revealing that pseudo-transitions in 1D become genuine first-order phase transitions in 2D, with the Widom line providing a new interpretative framework.

Contribution

It extends a class of frustrated 1D models to 2D, demonstrating the emergence of true phase transitions and the persistence of Widom lines.

Findings

Pseudo-transitions become first-order phase transitions in 2D.

The Widom line characterizes the transition and persists above a bi-critical point.

Provides a new interpretation of 1D pseudo-transitions in a 2D context.

Abstract

There has been much recent interest devoted to a class of frustrated one-dimensional statistical mechanics lattice models which exhibit sharp thermodynamics. In this work, we study an extension of one of these models to two dimensions; the Ising model on a decorated bilayer lattice. We show that the pseudo-transitions of the one-dimensional models become a real first order phase transition in this two-dimensional analogue. Moreover, the pseudo-transition is found to still exist above a bi-critical point. This can be characterised as a Widom line, which allows a re-interpretation of the physics in the previously studied one-dimensional models.