Accurate electronic ground- and excited-state properties of 2D CrI₃ and its heterostructures

The recent explosion of research into 2D materials has been largely motivated by promises of new confinement-driven excitonic and polaronic physics of potential use in future microelectronics. In particular, highly-correlated materials like 2D CrI₃ and WTe₂ are viable candidates for introducing coupled excitonic and magnetic physics into engineered vdW heterostructures. Here, we both outline progress in a new Diffusion Monte Carlo (DMC)-based method for predicting exciton binding energies (EBE’s) in monolayer CrI₃, and investigate induced magnetic and electronic effects in a CrI₃/1T’-WTe₂ bilayer (BL) using Density Functional Theory and Wannier90, benchmarked against DMC calculations. Our prediction of EBE’s utilizes DMC-obtained quasiparticle gaps and features an excited-state single-determinant Slater-Jastrow trial wavefunction built from natural orbitals obtained from a selected configuration interaction (sCI) expansion of localized, mean-field single-particle orbitals. We also quantify induced charge transfer, magnetic, and topological effects in BL CrI₃/1T’-WTe₂, and conclude with avenues for extending EBE results to the prediction of bilayer EBE’s.