The presence of chalcogen vacancies in monolayer transition metal dichalcogenides (TMDs) leads to excitons with mixed localized-delocalized character and to reduced valley selectivity. Recent experimental advances in defect design in TMDs allow for a close examination of such mixed exciton states as a function of their degree of circular polarization under external magnetic fields, revealing strongly varying defect-induced magnetic properties. A theoretical understanding of these observations and their physical origins demands a predictive, structure-sensitive theory. In this work, we study the effect of chalcogen vacancies on the exciton magnetic properties in monolayer MoS2. Using many-body perturbation theory, we show how the complex excitonic picture associated with the presence of defects -- with reduced valley and spin selectivity due to hybridized electron-hole transitions -- leads to structurally-controllable exciton magnetic response. We find a variety of g-factors with changing magnitudes and sign depending on the exciton energy and character. Our findings suggest a pathway to tune the nature of the excitons -- and by that their magneto-optical properties -- through defect architecture.
@article{arxiv.2203.14125,
title = {Tunable magneto-optical properties in MoS$_2$ via defect-induced exciton transitions},
author = {Tomer Amit and Daniel Hernangómez-Pérez and Galit Cohen and Diana Y. Qiu and Sivan Refaely-Abramson},
journal= {arXiv preprint arXiv:2203.14125},
year = {2024}
}