Two-dimensional ferromagnetic semiconductor CrXP: first-principles calculations and Monte Carlo simulations.

Two-dimensional room-temperature intrinsic ferromagnetic semiconductors have attracted widespread attention due to their applications in spintronic devices. However, it is difficult for the material to have a Curie temperature above room temperature according to the Mermin-Wagner theorem. By using the method of band engineering, we design a new promising two-dimensional room-temperature intrinsic ferromagnetic semiconductor CrXP (X = P, As, Sb) with large magnetization. The formation of a semiconducting gap for CrXP is discussed in terms of hybridization, occupation and distribution of electronic states and charge transfer. Large magnetic moments of about 6.16-6.37 originate from the occupation of Cr-d electrons in the crystal field. Competition between Cr-d-Cr-d and Cr-d-X-p-Cr-d exchange interactions leads to the emergence of a ferromagnetic order phase. Furthermore, Curie temperatures, approaching 278 K, 464 K and 1590 K for CrP, CrAsP and CrSbP, are estimated by employing Monte Carlo simulations based on the Heisenberg model. The magnetic anisotropy energy of CrXP is discussed using magnetic second-order perturbation theory. In addition, CrXP possesses excellent thermodynamic, dynamical, thermal and mechanical stabilities and can overcome its own gravity to retain its planar structure without the support of the substrate. These above-mentioned advantages will offer some valuable insights into two-dimensional intrinsic ferromagnetic semiconductor CrXP in spintronic devices.