Energy renormalizations of resident carriers and excitons in transition metal dichalcogenide monolayers

TL;DR

This paper presents a theoretical study of energy renormalizations in resident carriers and excitons in transition metal dichalcogenide monolayers, highlighting the role of dynamical screening and exchange interactions, and comparing results with recent experiments.

Contribution

It introduces a new theoretical framework for understanding energy renormalizations in TMD monolayers, emphasizing the impact of dynamical screening and exciton envelope functions.

Findings

Energy renormalization of resident carriers is significant under strong magnetic fields.

Weak energy shifts of excitonic resonances are explained despite large carrier renormalizations.

Renormalization depends on the exciton envelope function, not just individual electron and hole contributions.

Abstract

Energy renormalizations of resident carriers and excitons are studied theoretically, and compared with recent experiments of electrostatically-doped WSe$_2$ monolayers. The calculated energy renormalization of resident carriers, subjected to strong out-of-plane magnetic field, reveals the importance of dynamical screening in transition metal dichalcogenides. The energy renormalization of tightly bound excitons is analyzed through the exchange interaction between the electron (or hole) component of the exciton and resident carriers that share the same spin and valley quantum numbers. Our theory explains the weak energy shift of excitonic resonances despite the strong energy renormalization of resident carriers. We identify the dependence of the energy renormalization on the envelope function of a tightly-bound exciton, showing that unlike free electron-hole pairs, this energy renormalization is not the added renormalizations of a resident electron and resident hole.