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

We explore the creation of skyrmions and antiskyrmions as a function of temperature and magnetic field. We use an atomistic extended Heisenberg model derived from density functional theory calculations for the ultra-thin film system Pd/Fe/Ir(111) to show that temperature induces non-zero skyrmion and antiskyrmion densities. We demonstrate that the density of skyrmions and antiskyrmions increases independently of the applied temperature and magnetic field, and that the different magnetic phases are determined by the imbalance and relation between these densities. We use the parallel tempering Monte Carlo method in order to reliably compute the B-T phase diagram and critical temperatures in the presence of frustrated interactions. We identify an intermediate phase in which there is no spatial long-range order but there is a finite difference between the skyrmion and antiskyrmion densities.