Regensburg 2022 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: 2D Materials 2 (joint session HL/CPP/DS)
CPP 10.3: Vortrag
Montag, 5. September 2022, 15:30–15:45, H36
Ab initio description of valley-selective circular dichroism — •Maximilian Schebek1, Yiming Pan2, Cecilia Vona1, Claudia Draxl1, and Fabio Caruso2 — 1Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany — 2Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
By enabling control of valley degrees of freedom, valley-selective circular dichroism (VSCD) has become a key concept in valleytronics. In this work, we present an ab initio many-body theory of VSCD based on the Bethe-Salpeter equation. Our approach provides a new route to accurately predict the degree of valley polarization upon absorption of circularly polarized light. With the example of monolayer transition-metal dichalcogenides, we further show that valley excitons - bound electron-hole pairs formed at either the K or K valley upon absorption of circularly-polarized light - are chiral quasiparticles characterized by a finite orbital angular momentum (OAM). Beside governing the interaction with circularly polarized light, the OAM results in a finite magnetization of excitons, which in turn provides a route for the interaction of excitons with external magnetic fields and other spin-orbital degrees of freedom.