Electronic and magnetic properties of charged point defects in monolayer CrI.

The two-dimensional magnetic material CrI has gained considerable attention owing to its promising applications in photoelectric and spin-related devices. Recently, various structural defects in CrI have been identified; however, the charge states of these defects have been mainly ignored. Here, we report on an investigation of the charged defects in monolayer CrI, focused on the electronic and magnetic properties of the five most stable point defects using first-principles calculations. For positively charged I vacancies and negatively charged Cr vacancies, a blue- and red-shift of defect states near the Fermi level can be observed because of the atom relaxation. Our results also indicate that, among the five defects, the Cr interstitial defect has the smallest ionization energy of 0.34 eV, which makes its ionization easiest. Furthermore, a 0.2 enhancement of the magnetic moment on the nearest Cr atom can be found for the I vacancy and Cr interstitial defect. The investigation contributes to the atomic-scale comparison and understanding of the charged defects of monolayer CrI.