Nonmetallic Atoms Induced Magnetic Anisotropy in Monolayer Chromium Trihalides

Abstract

Magnetic anisotropy (MA) is crucial for realization of long-range magnetic order in two-dimensional (2D) materials and the long-range ferromagnetic order was experimentally demonstrated in monolayer CrI3. Here, using first principles calculations, we systematically investigate the electronic structure and magnetic anisotropy of monolayer chromium trihalides, including CrCl3, CrBr3, and CrI3. We find that the perpendicular magnetic anisotropy in monolayer CrBr3 and CrI3 are mainly induced by the spin-polarized p-orbitals of nonmetallic Br and I atoms but not the magnetic Cr atom. Moreover, the magnetic anisotropy energy (MAE) of the I atom can reach up to 0.71 meV/atom, which is comparable to that of metallic Fe atom at the Fe/MgO interface. By analyzing the density of states and the p-orbital-resolved MAE of I and Br atoms based on the second-order perturbation theory, we find that the matrix element difference between the same spin p y and p x orbitals of I and Br atoms contributes most to their MAEs. Furthermore, the MAEs of each I and Br atom possess 2-fold symmetry and the MAEs of all I­(Br) atoms show 6-fold symmetry in-plane, whereas the sum of the MAEs of these I and Br atoms along all in-plane magnetized axes is an identical value. These findings will benefit for a deeper understanding of the MA in 2D intrinsic ferromagnets and push 2D spintronic applications.

Intrinsic 2D-XY ferromagnetism in a van der Waals monolayer

“…2E, inset) are on the order of 0.5 to 0.6 T (corresponding to anisotropy energies of 0.09 to 0.11 meV). These values are much larger than those anticipated from first-principles calculations of a CrCl 3 monolayer ( 32 , 37 , 38 ), which range from 0.031 to 0.055 meV/Cr, and also turn out to be slightly larger than the critical field anisotropy in the antiferromagnetic bulk (0.3 to 0.5 T) ( 26 , 33 ) and in bilayer CrCl 3 (0.23 T) ( 29 ). A stable ferromagnetic ordering was not expected a priori when reducing the dimensionality of the few-layer antiferromagnetic system down to the monolayer, as it was unclear whether the removal of the interlayer exchange interaction would leave the intralayer ferromagnetic behavior intact.…”

Band inversion and switchable magnetic properties of two-dimensional RuClF/WSe2 van der Waals heterostructures

“…Non-metallic atoms with strong SOC can provide non-negligible MAE. 62 The materials with PMA have a wider range of applications than those with IMA, 63 so the MAE of RuClF/WSe 2 heterostructure is switched to favor applications.…”

Two dimensional Janus RuXY (X, Y = Br, Cl, F, I, X ≠ Y) monolayers: ferromagnetic semiconductors with spontaneous valley polarization and tunable magnetic anisotropy

“…3, there is no imaginary frequency in the first Brillouin zone, which proved the dynamic stability of the Janus monlayers. 52 The Berry curvature of RuBrCl, RuBrF and RuClF was calculated and the results are shown in Fig. 4.…”