Two-dimensional ferromagnetic semiconductor Cr₂XP: 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 Cr₂XP (X = P, As, Sb) with large magnetization. The formation of a semiconducting gap for Cr₂XP is discussed in terms of hybridization, occupation and distribution of electronic states and charge transfer. Large magnetic moments of about 6.16-6.37μ_B 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 Cr₂P₂, Cr₂AsP and Cr₂SbP, are estimated by employing Monte Carlo simulations based on the Heisenberg model. The magnetic anisotropy energy of Cr₂XP is discussed using magnetic second-order perturbation theory. In addition, Cr₂XP 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 Cr₂XP in spintronic devices.