Tunable magneto-optical properties in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>MoS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> via defect-induced exciton transitions
Tomer Amit, Daniel Hernangómez‐Pérez, Galit Cohen, Diana Y. Qiu, Sivan Refaely‐Abramson
Abstract
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 ${\mathrm{MoS}}_{2}$. 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 a 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.