Effect of intravalley and intervalley electronhole exchange on the nonlinear optical response of monolayer MoSe_{2}
Abstract
The coherent thirdorder nonlinear response of monolayer transitionmetal dichalcogenide semiconductors, such as MoSe_{2}, is dominated by the nonlinear exciton response, as well as biexciton and trion resonances. The fact that these resonances may be spectrally close together makes identification of the signatures, for example in differential transmission (DT), challenging. Instead of focusing on explaining a given set of experimental data, a systematic study aimed at elucidating the roles of intravalley and intervalley longrange electronhole (e h ) exchange on the DT spectra is presented. Previous works have shown that the e h longrange exchange introduces a linear leadingorder term in the exciton dispersion. Based on a generalized LippmannSchwinger equation, we show that the presence of this linear dispersion term can reduce the biexciton binding energy to zero, contrary to the conventional situation of quadratic dispersion where an arbitrarily weak (wellbehaved) attractive interaction always supports bound state(s). The effects of spin scattering and the spinorbit interaction caused by e h exchange are also clarified, and the DT line shape at the exciton and trion resonance is studied as a function of e h exchange strength. In particular, as the exciton line shape is determined by the interplay of linear exciton susceptibility and the boundstate twoexciton resonance in the T matrix, the line shape at the trion is similarly determined by the interplay of the linear trion susceptibility and the boundstate excitontrion resonance in the T matrix.
 Publication:

Physical Review B
 Pub Date:
 December 2021
 DOI:
 10.1103/PhysRevB.104.245434
 arXiv:
 arXiv:2108.00091
 Bibcode:
 2021PhRvB.104x5434K
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics;
 Physics  Optics
 EPrint:
 Phys. Rev. B 104, 245434 (2021)