Tunable excited states in moiré superlattices
Max Planck Quantum Matter Seminar
- Date: Mar 3, 2022
- Time: 03:00 PM - 04:00 PM (Local Time Germany)
- Speaker: Xiaoqin Elaine Li
- University of Texas at Austin
- Location: online via Zoom
- Host: Gregor Jotzu
![Tunable excited states in moiré superlattices Tunable excited states in moiré superlattices](/event_images/30218-1645776679.jpeg)
In van der Waals bilayers, the strict requirement of lattice matching at
the interface is lifted. The periodic changes in atomic alignment lead
to the formation of an in-plane superlattice, known as the moiré
superlattice. The twist angle acts as a unique knob to control the
material properties. Instead of focusing on the correlated ground states
often discussed in the literature, I will discuss how excited states
and collective excitations are modified. The lifetimes of bound
electron-hole pairs (i.e. excitons) can be varied by one order of
magnitude when the twist angle of a MoSe2/WSe2 bilayer is varied from 1°
to 3.5°. The phonon spectra evolution in MoS2 bilayers reflects lattice
reconstruction over a surprisingly large range of twist angles from
zero to 6°. If time permits, I will share some new results on
topological magnons that exhibit long lifetimes near the Brillouin zone
boundary.