Atomic-scale defects in the two-dimensional ferromagnet CrI₃ from first principles

Abstract

The family of atomically thin magnets holds great promise for a number of prospective applications in magneto-optoelectronics, with CrI3 arguably being its most prototypical member. However, the formation of defects in this system remains unexplored to date. Here, we investigate native point defects in monolayer CrI3 by means of first-principles calculations. We consider a large set of intrinsic impurities and address their atomic structure, thermodynamic stability, diffusion and aggregation tendencies as well as local magnetic moments. Under thermodynamic equilibrium, the most stable defects are found to be either Cr or I atomic vacancies along with their complexes, depending on the chemical potential conditions. These defects are predicted to be quite mobile at room temperature and to exhibit a strong tendency to agglomerate. In addition, our calculations indicate that the defect-induced deviation from the nominal stoichiometry largely impacts the local magnetic moments, thereby suggesting a marked interplay between magnetism and disorder in CrI3. Overall, this work portrays a comprehensive picture of intrinsic point defects in monolayer CrI3 from a theoretical perspective.

Emerging oxidized and defective phases in low-dimensional CrCl3

“…21 Some theoretical studies on Cr-trihalides highlighted the role of defects in determining the electronic structure. [22][23][24][25][26][27] Specifically, when Cr vacancy-defects are considered, a transition to a half-metal is observed in all Cr-trihalides, 22,24,27 while Cl vacancies narrow the band gap, as found in YCl 3 . 23 In this study, we investigate defective CrCl 3 surface and experimentally demonstrate the existence of surface ordered oxidized and Cl defective phases of CrCl 3 elucidating their role on the electronic structure.…”

DMRG and Monte Carlo studies of $\textrm{CrI}_3$ magnetic phases and the phase transition

“…CrI 3 can exhibit various types of magnetic ordering by introducing defects [48], strain [49,50] and charge doping [50,51]. We have analyzed the role of correlation effects and studied phase transitions in the XXZ model on a honeycomb lattice, which is an effective model for CrI 3 .…”

“…Appropriate parameters for CrI 3 have been determined using ab-initio methods [46,47]. Other phases can be achieved in CrI 3 by introducing defects [48], strain [49,50] and charge doping [50,51], which effectively enhance magnetic anisotropy.…”

Prediction of Chalcogen‐Doped VCl3 Monolayers as 2D Ferromagnetic Semiconductors with Enhanced Optical Absorption

“…We can attribute the AFM-FM phase transition in Sdoped VCl 3 monolayers to the lattice distortion induced by S dopant, similar to defect-induced magnetic phase transition in CrI 3 monolayer. [39] According to the Goodenough-Kanamori-Anderson (GKA) rules: if a cation-anion-cation bond angle is nearly 90 • , the system prefers FM order, conversely, it is AFM for 180 • . [40] The intrinsic AFM 2 −VCl 3 monolayer has two kinds of V−Cl−V bonding angle 1 = 97.1 • and 2 = 95.1 • (see Figure S2, Supporting Information).…”