  We determined the magnetic B-T phase diagram of PdFe bilayer on Ir(111)
surface by performing Monte Carlo and spin dynamics simulations based on an
effective classical spin model. The parameters of the spin model were
determined by ab initio methods. At low temperatures we found three types of
ordered phases, while at higher temperatures, below the completely disordered
paramagnetic phase, a large region of the phase diagram is associated with a
fluctuation-disordered phase. Within the applied model, this state is
characterized by the presence of skyrmions with finite lifetime. According to
the simulations, this lifetime follows the Arrhenius law as a function of
temperature.
