Towards controlling local excitons with chiral edge states in the terraced bilayer 1T'-WTe2/CrI3

The promise of new confinement-driven excitonic and spintronic physics in 2D materials has put them at the forefront of next-generation microelectronics research. In particular, 2D materials like monolayer (ML) CrI3 and WTe2 exhibit interesting magnetooptical and topological properties which can be combined to realize novel multifunctional heterostructures. Here, we present: (1) a new scheme for describing local excitons in ML CrI3 which features an excited-state single-determinant of natural orbitals obtained from iterative selected configuration interaction expansions starting from mean-field single-particle orbitals, and (2) evidence for the possibility of realizing dissipationless chiral edge states in a terraced CrI3/WTe2 bilayer (BL) heterostructure. Importantly, we recover the same local exciton shape in CrI3 as GW-BSE but use only a single determinant of optimized orbitals at a single k-point to do so; we also describe the atomic orbital characteristics of this exciton for the first time. Lastly, we quantify charge transfer, magnetic, and topological effects in BL CrI3/1T'-WTe2, using Density Functional Theory and hybrid Wannier charge centers, finding that CrI3 induces ferromagnetism on W atoms in 1T'-WTe2 and renders the bilayer topologically trivial. This suggests the possibility of realizing chiral edge conductance at the interface of a topological nonmagnetic Weyl semimetal by covering part of it with a 2D ferromagnet.