B-T phase diagram of Pd/Fe/Ir(111) computed with parallel tempering Monte Carlo

TL;DR

This paper uses advanced Monte Carlo simulations on an atomistic spin model to map the temperature and magnetic field phase diagram of Pd/Fe/Ir(111), revealing five distinct magnetic phases and the influence of frustrated exchange interactions.

Contribution

It introduces a reliable computational approach combining parallel tempering Monte Carlo with atomistic spin models to accurately determine phase diagrams of complex magnetic systems.

Findings

Identification of five magnetic phases including skyrmion lattice and spin spiral.

Critical temperatures depend on magnetic field, contrary to previous assumptions.

Frustrated exchange interactions significantly influence the phase diagram.

Abstract

We use an atomistic spin model derived from density functional theory calculations for the ultra-thin film Pd/Fe/Ir(111) to show that temperature induces coexisting non-zero skyrmion and antiskyrmion densities. We apply the parallel tempering Monte Carlo method in order to reliably compute thermodynamical quantities and the B-T phase diagram in the presence of frustrated exchange interactions. We evaluate the critical temperatures using the topological susceptibility. We show that the critical temperatures depend on the magnetic field in contrast to previous work. In total, we identify five phases: spin spiral, skyrmion lattice, ferromagnetic phase, intermediate region with finite topological charge and paramagnetic phase. To explore the effect of frustrated exchange interactions, we calculate the B-T phase diagram, when only effective exchange parameters are taken into account.