Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
Journal article, 2021

Due to a strong Coulomb interaction, excitons dominate the excitation kinetics in two-dimensional (2D) materials. While Coulomb scattering between electrons has been well studied, the interaction of excitons is more challenging and remains to be explored. As neutral composite bosons consisting of electrons and holes, excitons show nontrivial scattering dynamics. Here, we study exciton-exciton interaction in transition-metal dichalcogenides and related van der Waals heterostructures on microscopic footing. We demonstrate that the crucial criterion for efficient scattering is a large electron/hole mass asymmetry, giving rise to internal charge inhomogeneities of excitons and emphasizing their cobosonic substructure. Furthermore, both exchange and direct exciton-exciton interactions are boosted by enhanced exciton Bohr radii. We also predict an unexpected temperature dependence that is usually associated with phonon-driven scattering, and we reveal an orders of magnitude stronger interaction of interlayer excitons due to their permanent dipole moment. The developed approach can be generalized to arbitrary material systems and will help to study strongly correlated exciton systems, such as moire super lattices.

Temperature distribution

Transition metals

Superconducting materials

Van der Waals forces

Monolayers

Author

Daniel Erkensten

Chalmers, Physics, Condensed Matter and Materials Theory

Samuel Brem

Philipps-Universität Marburg

Ermin Malic

Philipps-Universität Marburg

Chalmers, Physics, Condensed Matter and Materials Theory

Physical Review B

24699950 (ISSN) 24699969 (eISSN)

Vol. 103 4 045426

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics

DOI

10.1103/PhysRevB.103.045426

More information

Latest update

3/17/2021