Skyrmions in Monolayer van der Waals 2D Magnets

In this work, using Landau-Lifshitz Gilbert (LLG) model and first-principle calculations we demonstrate the occurrence of skyrmions in monolayer CrI₃. We considered a paramagnetic state and apply a range of magnetic fields from 0 T to 1.5 T. We found the system evolves under normal conditions (i.e., the time evolution under the influence of exchange and anisotropic interactions) to energetically favourable skyrmionic ground state. We derive the Heisenberg exchange (J), uniaxial magnetocrystalline anisotropy (K) and Dzyaloshinskii-Moriya interaction (DMI) parameters for monolayer CrI₃. Our calculations revealed that the isolated skyrmionic spin textures evolved in the order of a few picoseconds for a wide range of magnetic field. We found the chiral domain walls or helical states in the 2D monolayer CrI₃ along with the presence of skyrmions at low magnetic field strengths. However, with increasing strength of the magnetic field, the density of occurrence of chiral domains reduces converging and forming skyrmions. It is also observed that with the increase in the field strength the size of stable skyrmions reduces.