Phase diagram of a three-dimensional dipolar Ising model with textured Ising axes

TL;DR

This study uses Monte Carlo simulations to explore the phase diagram of a textured dipolar Ising model, revealing paramagnetic, ferromagnetic, and spin-glass phases influenced by axis distribution, relevant for magnetic nanoparticle supercrystals.

Contribution

It introduces a model with textured Ising axes on a face centered cubic lattice, linking random and aligned dipole models, and maps the phase diagram including reentrant spin-glass behavior.

Findings

Identified paramagnetic, ferromagnetic, and spin-glass phases.

Discovered reentrant spin-glass phase near ferromagnetic boundary.

Linked axis distribution texture to magnetic phase behavior.

Abstract

We study from tempered Monte Carlo simulations the magnetic phase diagram of a textured dipolar Ising model on a face centered cubic lattice. The Ising coupling of the model follow the dipole-dipole interaction. The Ising axes are distributed with a uniaxial symmetry along the $\hat{z}$ direction with a gaussian probability density of the polar angles. This distribution provides a quenched disorder realization of the dipolar Ising model making a continuous link between the parallel axes dipoles and the random axes dipole models. As expected the phase diagram presents three distinctive phases: paramagnetic, ferromagnetic and spin-glass. A quasi long range ferromagnetic and a reentrant spin-glass phases are obtained in the vicinity of the ferromagnetic spin-glass line. This model provides a way to predict the magnetic phases of magnetic nanoparticles supracrystals in terms of the texturation of the easy axes distribution in the strong anisotropy limit.