First-principles calculations of few-layer Chromium Trihalides CrCl3, CrBr3, and CrI3

One of the latest advances in the field of two-dimensional (2D) materials is the discovery of intrinsic ferromagnetism in monolayers of CrGeTe3 and CrI3– in these structures, thermal fluctuations could be counteracted by magnetic anisotropy, as required by the Mermin-Wagner Theorem. Combining ferromagnetism in 2D materials is desirable as a means to expand the possibilities for microelectronic devices. In this work, using first-principles calculations, we present a detailed study of the energetics, atomic structures, electronic structures, and lattice dynamics of Chromium Trihalides CrCl3, CrBr3, and CrI3 down to the two-dimensional limit, as all three compounds exhibit a strong intralayer ferromagnetic coupling. Calculations using various exchange-correlation functionals and pseudopotentials are tested and compared with experimental data. The effect of strain and stacking geometry in the magnetic properties of these materials will also be discussed.