Bipolar Doping by Intrinsic Defects and Magnetic Phase Instability in Monolayer CrI₃

As a two-dimensional direct band gap semiconductor with unique electronic and magnetic properties, monolayer chromium triiodide (CrI3) has a great potential for spintronic applications. Under the guidance of the defect theory, we adopt first-principles calculation to determine the structural, thermodynamic, electronic, and magnetic properties of point defects of monolayer CrI3. Twenty kinds of point defects, including vacancies, interstitial, substitution, and bond-rotation defects have been investigated. Either the metalloid or metallic single atom vacancies is energetically stable depends on the chemical potential of iodide, leading to the intrinsic n-type and p-type dopings, respectively. More interestingly, a ferromagnetic to antiferromagnetic transition of the magnetic phase can be induced for most type of point defects, which can be explained by a simple Heisenberg model. The content of present investigation contributes to the atomic-scale understanding of the electric and magnetic properties of monolayer CrI3.