Spin-defect characteristics of single sulfur vacancies in monolayer $\text{MoS}_2$

TL;DR

This study investigates the spin and optical properties of sulfur vacancy defects in monolayer MoS2, revealing their potential as tunable quantum emitters with spin-valley selectivity for quantum technology applications.

Contribution

It provides detailed high-field magneto-photoluminescence analysis of sulfur vacancy defects, identifying their electronic structure and spin-valley characteristics, and compares findings with ab-initio calculations.

Findings

Localized emitters with wavefunction extent of ~3.5 nm

Valley-Zeeman splitting indicates spin-valley selectivity

Optical polarization tunability linked to Fermi level

Abstract

Single spin defects in 2D transition-metal dichalcogenides are natural spin-photon interfaces for quantum applications. Here we report high-field magneto-photoluminescence spectroscopy from three emission lines (Q1, Q2 and Q*) of He-ion induced sulfur vacancies in monolayer $\text{MoS}_2$. Analysis of the asymmetric PL lineshapes in combination with the diamagnetic shift of Q1 and Q2 yields a consistent picture of localized emitters with a wavefunction extent of $\sim$ 3.5 nm. The distinct valley-Zeeman splitting in out-of-plane $B$-fields and the brightening of dark states through in-plane $B$-fields necessitates spin-valley selectivity of the defect states and lifted spin-degeneracy at zero field. Comparing our results to ab-initio calculations identifies the nature of Q1 and Q2 and suggests that Q* is the emission from a chemically functionalized defect. Analysis of the optical degree of circular polarization reveals that the Fermi level is a parameter that enables the tunability of the emitter. These results show that defects in 2D semiconductors may be utilized for quantum technologies.