Many-Body Simulation of Two-Dimensional Electronic Spectroscopy of Excitons and Trions in Monolayer Transition-Metal Dichalcogenides

TL;DR

This paper develops a many-body simulation framework for two-dimensional electronic spectroscopy to study excitons and trions in monolayer transition-metal dichalcogenides, revealing quantum coherence effects and their relation to material properties.

Contribution

It introduces a many-body formalism combined with a simplified model to simulate nonlinear spectroscopy of excitons and trions, aligning well with experimental data.

Findings

Simulated spectra match experimental results.

Quantum coherence between excitons and trions is confirmed.

Coherence times differ between molybdenum and tungsten compounds.

Abstract

We present a many-body formalism for the simulation of time-resolved nonlinear spectroscopy and apply it to study the coherent interaction between excitons and trions in doped transition-metal dichalcogenides. Although the formalism can be straightforwardly applied in a first-principles manner, for simplicity we use a parameterized band structure and a static model dielectric function, both of which can be obtained from a calculation using the $GW$ approximation. Our simulation results shed light on the interplay between singlet and triplet trions in molybdenum- and tungsten-based compounds. Our two-dimensional electronic spectra are in excellent agreement with recent experiments and we accurately reproduce the beating of a cross-peak signal indicative of quantum coherence between excitons and trions. Although we confirm that the quantum beats in molybdenum-based monolayers unambigously reflect the exciton-trion coherence time, they are shown here to provide a lower-bound to the coherence time of tungsten analogues due to a destructive interference emerging from coexisting singlet and triplet trions.