Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 53: 2D Semiconductors and van der Waals Heterostructures V
HL 53.6: Talk
Thursday, March 20, 2025, 16:30–16:45, H15
Beyond the K-Valley: Exploring Unique Trion States in Indirect Band Gap Monolayer WSe2 — •Franz Fischer1,2, Carl Emil Mørch Nielsen1, and Gabriel Bester1 — 1University of Hamburg, Institute of Physical Chemistry, 22761 Hamburg, Germany — 2Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
Atomically thin layers of transition metal dichalcogenides are of great interest due to their exceptional electronic and optical properties. Their lack of inversion symmetry and strong spin-orbit interaction from heavy metal atoms leads to an additional valley degree of freedom and significant spin splittings in the Brillouin zone. The reduced dimensionality and dielectric screening make these materials ideal for studying Coulomb-bound many-body states, such as excitons and trions.
We will discuss calculations of the optical properties of monolayer WSe2 using ab initio many-body screened configuration interaction. We’ll highlight our findings on additional species of negatively charged trions including the Q-valley, which we found to be more energetically favorable than those in the K-valley. Our results align well with experimental data and provide new insights into previously observed but unexplained optical features. Furthermore, we will analyze the many-body interactions that reveal the mechanisms behind the increased singlet-triplet splitting and the redshifted energies in the Q-valley trions compared to those in the K-valley.
Keywords: Excitons; Trions; Transition Metal Dichalcogenides; Configuration Interaction