Ab initio calculations of spin-nonconserving exciton-phonon scattering in monolayer transition metal dichalcogenides

Abstract

We investigate the spin-nonconserving relaxation channel of excitons by their couplings with phonons in two-dimensional transition metal dichalcogenides using $\text{ab initio}$ approaches. Combining $\text{GW}$-Bethe-Salpeter equation method and density functional perturbation theory, we calculate the electron-phonon and exciton-phonon coupling matrix elements for the spin-flip scattering in monolayer WSe${}_{\text{2}}$, and further analyze the microscopic mechanisms influencing these scattering strengths. We find that phonons could produce effective in-plane magnetic fields which flip spin of excitons, giving rise to relaxation channels complimentary to the spin-conserving relaxation. Finally, we calculate temperature-dependent spin-flip exciton-phonon relaxation times. Our method and analysis can be generalized to study other two-dimensional materials and would stimulate experimental measurements of spin-flip exciton relaxation dynamics.

7 pages, 6 figures

References in corpus (5)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Intrinsic spin Hall effect in monolayers of group-VI dichalcogenides: A first-principles study
• Emerging Photoluminescence from the Dark-Exciton Phonon Replica in Monolayer WSe2

Cited by in corpus (4)

• Exciton lifetime and optical linewidth profile via exciton-phonon interactions: Theory and first-principles calculations for monolayer MoS${}_2$
• Phonon-mediated exciton relaxation in two-dimensional semiconductors: selection rules and relaxation pathways
• Dissecting intervalley coupling mechanisms in monolayer transition metal dichalcogenides
• Wannier-Function-Based Approach to Coupled Exciton-Phonon-Photon Dynamics in Two-Dimensional Semiconductors