First-Principles Study of Influence of Charged and Neutral Vacancy Defects on Mechanical and Electronic Properties of Single Layer CrI3.

Intrinsically magnetic 2D materials provide an ideal platform for exploring magnetism in reduced dimensions and have attracted significant attention due to their potential applications in next-generation spintronic devices. The performance of such devices strongly depends on the structural quality and defect morphology of the underlying 2D materials. Point defects play a crucial role, acting either as beneficial tools for property engineering or as detrimental factors leading to device degradation. Recently, atomic iodine vacancies (V I ), atomic chromium vacancies (V Cr ), and vacancy complexes (V CrI3 ) have been experimentally identified. Motivated by experimental findings, we investigate the influence of vacancy defects on the structural, mechanical, electronic, and magnetic properties of single-layer CrI3 in the present work. Although several theoretical studies have reported the electronic and magnetic properties of CrI3 single layer with vacancy defects, a systematic investigation of influence of vacancies on mechanical properties remains largely unexplored. Our calculations show that the presence of vacancies significantly degrades the elastic properties. For a defect concentration of 1.39%, the Young's modulus decreases to 20.88 and 16.66 N/m for V I and V Cr , respectively. For vacancy complexes with concentrations of 5.56% (V CrI3 ) and 9.72% (V CrI6 ), the Young's modulus further reduces to 18.28 and 16.20 N/m, respectively, compared to 24.12 N/m for the pristine system. This reduction indicates a softening of the single-layer CrI 3 due to vacancies. Furthermore, we find that the mechanical properties of charged and neutral defects do not differ significantly and are primarily governed by structural distortions. On the other hand, vacancy defects alter the electronic character, either transforming the system from semiconducting to half-metallic or leading to a reduction in the band gap. Importantly, the magnetic properties remain robust in the presence of vacancy defects. Overall, the present study provides insights into influence of vacancy defects on the mechanical and electronic properties of single layer CrI3, thereby improving our understanding of defect engineering in 2D magnetic materials.