Theory of the Coherent Response of Magneto-Excitons and Magneto-Biexcitons in Monolayer Transition Metal Dichalcogenides

TL;DR

This paper develops a microscopic theory to understand how magnetic fields influence the coherent optical responses of excitons and biexcitons in monolayer transition metal dichalcogenides, aiding future experimental interpretations.

Contribution

It introduces a nonlinear microscopic framework for analyzing magnetic-field effects on excitonic interactions in monolayer TMDs, including fine structure and oscillator strengths.

Findings

Magnetic fields induce specific fine structures in excitons and biexcitons.

The theory predicts coherent signatures observable in wave-mixing experiments.

Oscillator strengths are calculated for different magnetic field orientations.

Abstract

The recent accessibility of high quality, charge neutral monolayer transition metal dichalcogenides with narrow exciton linewidths at the homogeneous limit provides an ideal platform to study excitonic many-body interactions. In particular, the possibility to manipulate coherent exciton-exciton interactions, which govern the ultrafast nonlinear optical response, by applying an external magnetic field has not been considered so far. We address this discrepancy by presenting a nonlinear microscopic theory in the coherent limit for optical excitations in the presence of out-of-plane, in-plane, and tilted magnetic fields. Specifically, we explore the magnetic-field-induced exciton and biexciton fine structure and calculate their oscillator strengths based on a Heisenberg equations of motion formalism. Our microscopic evaluations of pump-probe spectra allow to interpret and predict coherent signatures in future wave-mixing experiments.