Theoretical prediction of Curie temperature in two-dimensional monolayer ferromagnets

Theoretical prediction of Curie temperature (TC) is of vital importance for the design spintronic devices of two-dimensional (2D) ferromagnetic materials. Widely used methods for estimating TC depend on mean-field theory. However, many mean-field methods often overestimate the TC due to the neglect of the local magnetic order above TC. Herein, based on mean-field theory and first-principles calculations, we propose an improved mean-field method to estimate TC more precisely, which includes the different contributions of multiple near-neighbor interactions. Taking 2D honeycomb ferromagnets of monolayer CrI3 and Cr2Ge2Te6 as examples, the trends of TC with biaxial strain are investigated via classic Monte Carlo (MC) simulations, different mean-field formulas, and our method. Importantly, the method we proposed is more accurate than many previous ones, the results of TC are in good agreement with MC simulations and experimental values. Remarkably, our method not only suitable for honeycomb lattice but it can be extended to predict the TC of other 2D lattices. Our work paves the way to accelerate the prediction and discovery of novel 2D ferromagnets for spintronic applications.