Emergence of composite many-body exciton states in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>WS</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>MoSe</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math> monolayers

Abstract

When electron-hole pairs (excitons) are photoexcited into semiconductors containing a Fermi sea of mobile charges, they can form bound states known variously as trions, tetrons, or exciton-polarons. Crucially, the interaction occurs with those mobile carriers possessing distinguishable quantum numbers (e.g., spin). In monolayer TMD semiconductors, the availability of both spin and valley quantum numbers allows excitons to interact, simultaneously, with more than one type of quantum-mechanically distinguishable carrier. This leads to new types of composite excitons (e.g., six-particle ``hexcitons''), which appear as distinct resonances in optical spectra.

Topics & Concepts