Effects of external magnetic field and out-of-plane strain on magneto-optical Kerr spectra in CrI₃ monolayer

Abstract

Magnetic semiconductors based on two-dimensional (2D) crystals have attracted attention owing to their intrinsic ferromagnetism and have potential for spintronic devices. Here, full-potential linearized augmented plane wave plus local orbitals method is used to explore the structural, electronic, magnetic, and magneto-optical properties of CrI monolayer. Our first-principles calculations show that CrI monolayer is a ferromagnetic indirect semiconductor with spin-up and spin-down band gaps of 1.23 and 1.90 eV, respectively, and a magnetic moment of 2.93 [Formula: see text] per Cr atom. Based on the macroscopic linear response theory, we systematically study the influences of external magnetic field and out-of-plane strain on the magneto-optical Kerr effect spectra in CrI monolayer. The Kerr rotation of CrI monolayer at 1.96 eV photon energy is [Formula: see text], which is consistent with the recent experiments. We find that the Kerr rotation reaches its maximum when the external magnetic field is perpendicular to CrI plane, while it is almost zero on turning the magnetic field in the plane. This result as well as the sizable magnetocrystalline anisotropy energy (MAE) of 0.79 meV verifies that CrI monolayer has a strong magnetic anisotropy with an out-of-plane easy axis. Further, applying out-of-plane compressive and tensile strain upon CrI monolayer, we observe a redshift of the Kerr rotation spectra with the increase of the strain and the peak values of the Kerr rotation increase correspondingly. The rich electronic and magnetic properties, especially the magneto-optical spectra, render CrI monolayer a promising 2D magnetic material for applications from sensing to data storage.

Interface depended electronic and magnetic properties of vertical CrI3/WSe2 heterostructures

“…Taking SOC effects into account, the total energies E m//a and E m//c can be achieved through noncollinear calculations, and then the MAE can be evaluated. Consistent with the previous calculations 12,18,19,21 and experimental results, 13,17 because of the strong SOC in the heavier iodine ions, 17 the easy axis for monolayer CrI 3 is outplane with MAE 0.73 meV per Cr atom.…”

“…16,18 The magnetism arises from the partially lled d orbitals of the Cr 3+ ion, and the magnetocrystalline anisotropy favours an out-plane spin orientation. 12 It has been demonstrated that the magnetic properties of CrI 3 can be controlled by strain, [19][20][21][22][23] electric elds 24-28 and magnetic elds. 21,29 To combine the advantages of two different 2D materials, stacking them into a heterostructure has been proven to be an effective way.…”

“…12 It has been demonstrated that the magnetic properties of CrI 3 can be controlled by strain, [19][20][21][22][23] electric elds 24-28 and magnetic elds. 21,29 To combine the advantages of two different 2D materials, stacking them into a heterostructure has been proven to be an effective way. 30,31 Until now, many kinds of 2D heterostructures have been fabricated successfully in experiments, [32][33][34] and their physical properties have been predicated theoretically.…”

Impact of oxygen defects on a ferromagnetic CrI3 monolayer

“…As can be seen, both the CBM and VBM occurs at the G-point of Brillouin zone, showing a semiconducting behaviour with the direct bandgap of 1.14 eV that is consistent with the previously reported results. [24][25][26] Fig. 5b presents the spindependent electronic band structure of the O-attached CrI 3 monolayer.…”

Advanced Materials and Device Architectures for Magnetooptical Spatial Light Modulators

“…It has been theoretically demonstrated that a silicene monolayer exhibits maximum of 8° and 13° respectively for Faraday and Kerr rotations in terahertz regime . Other 2D materials with MO properties that have been studied so far include phosphorene, molybdenum disulfide (MoS 2 ), tungsten diselenide (WSe 2 ), chromium triiodide (CrI 3 ), and Cr 2 Ge 2 Te 6 …”