Room-temperature single-layer 2D van der Waals ferromagnetic-CrXY3 hosting skyrmions

Two-dimensional (2D) van der Waals magnetic materials that host skyrmions are promising candidates for the next-generation memory devices. Here, we have predicted a class of 2D chromium-based monolayer ferromagnetic semiconducting materials with a Curie temperature (Tc) exceeding 320 K. We systematically studied their ferromagnetism and quantum transport properties by employing a combination of density functional calculations, Monte Carlo simulations, atomic spin dynamics simulations, and non-equilibrium Green function methods. These materials display topological magnetic spin texture, i.e., magnetic skyrmions, resulting from the competitions between magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). Furthermore, we observed the generation and annihilation of Néel skyrmion lattice and asymmetric bimeron lattice in the magnetic field, which can be controlled by an external magnetic field. By tuning the detailed spin configurations and skyrmion density, we can effectively manipulate the signs and magnitudes of the topological Hall conductance. Our results demonstrate the tunable topology and magnetism of the discovered 2D vdW CrXY3 materials, paving the way for skyrmion-based spintronic devices.