Two-dimensional intrinsic ferromagnetism in CrBr3 monolayer

The CrBr3 monolayer provides an ideal experimental platform to study the two-dimensional ferromagnetism. In this work, we theoretically study the intrinsic ferromagnetism of CrBr3 monolayer based on the anisotropic Heisenberg model with exchange interactions beyond the nearest neighbor and employing the double-time Green's function method. The Hamiltonian parameter values of the model are taken from the recently reported first-principles calculations. The spontaneous magnetization, Curie temperature, hysteresis loop, and magnon energy spectrum are calculated numerically, and the theoretical results are compared with the available experimental results as much as possible. The calculated Curie temperature of 30.5 K is well consistent with the two experimental measurements of 27 K and 34 K, which in turn support the magnetic parameters obtained from the first-principles calculations. Moreover, the theoretically calculated results of critical exponent describing the critical behavior of spontaneous magnetization and hysteresis loops agree qualitatively well with the experimental measurements.