Microphase Separation and modulated phases in a Coulomb frustrated Ising ferromagnet

TL;DR

This paper investigates a 3D Coulomb frustrated Ising model, revealing that competing interactions lead to microphase separation and modulated phases, with a fluctuation-induced first-order transition confirmed through Monte Carlo simulations.

Contribution

It provides the first extensive Monte Carlo evidence for fluctuation-induced first-order transitions in a Coulomb frustrated Ising model.

Findings

Microphase separation transition is first-order.

Presence of various modulated phases at low temperatures.

Strong simulation evidence supporting fluctuation-induced transition.

Abstract

We study a 3-dimensional Ising model in which the tendency to order due to short-range ferromagnetic interactions is frustrated by competing long-range (Coulombic) interactions. Complete ferromagnetic ordering is impossible for any nonzero value of the frustration parameter, but the system displays a variety of phases characterized by periodically modulated structures. We have performed extensive Monte-Carlo simulations which provide strong evidence that the microphase separation transition between paramagnetic and modulated phases is a fluctuation-induced first-order transition. Additional transitions to various commensurate phases may also occur when further lowering the temperature.