Topological Devil's staircase in a constrained kagome Ising antiferromagnet

TL;DR

This paper investigates a constrained kagome Ising antiferromagnet, revealing a topological devil's staircase of phases due to infinite first and third neighbor couplings, with unique defect condensation and partial order phenomena.

Contribution

It uncovers a novel topological devil's staircase in a constrained kagome Ising model, highlighting unique phase transitions and defect structures not seen in similar models.

Findings

Infinite series of first-order transitions with defect condensation

Partial order with zero-energy domain walls

Quantized defect numbers leading to a devil's staircase

Abstract

We show that the constrained Ising model on the kagome lattice with infinite first and third neighbor couplings undergoes an infinite series of thermal first-order transitions at which, as in the Kasteleyn transition, linear defects of infinite length condense. However, their density undergoes abrupt jumps because of the peculiar structure of the low temperature phase, which is only partially ordered and hosts a finite density of zero-energy domain walls. The number of linear defects between consecutive zero-energy domain walls is quantized to integer values, leading to a devil's staircase of topological origin. By contrast to the devil's staircase of the ANNNI and related models, the wave-vector is not fixed to commensurate values inside each phase.