First-principles study of electronic, magnetic and vibrational properties in two-dimensional materials

Abstract

We apply the density-functional theory to study various phases (including nonmagnetic (NM), anti-ferromagnetic (AFM), and ferromagnetic (FM)) in monolayer magnetic chromium trihalides CrX3 (with X=Cl, Br, and I). Detailed calculations of their energetics, atomic structures, electronic structures, and Raman spectra have been carried out. It is found that: (1) the magnetic anisotropy energy and Curie temperatures can be tuned with the inclusion of biaxial strain; (2) the electronic band topologies as well as the nature of direct and indirect band gaps in either AFM or FM phases exhibit delicate dependence on the magnetic ordering and spin-orbit coupling; and (3) the phonon modes involving Cr atoms are particularly sensitive to the magnetic ordering. Our results not only provide a detailed guiding map for experimental characterization and tunability of CrX3 magnetic properties, but also reveal how the evolution of magnetism can be tracked by its lattice dynamics and Raman response.