Condensed Matter Seminar: Cyprian Lewandowski

Event time: 
Thursday, November 14, 2019 - 1:00pm to 2:00pm
Sloane Physics Laboratory (SPL), Room 52 See map
217 Prospect Street
New Haven, CT 06511
Event description: 

Intrinsically undamped plasmon modes in narrow electron bands
Surface plasmons in 2-dimensional electron systems with narrow Bloch bands feature an interesting regime in which Landau damping (dissipation via electron-hole pair excitation) is completely quenched. This surprising behavior is made possible by strong coupling in narrow-band systems characterized by large values of the “fine structure” constant α=e2/ℏκvF. We will show that dissipation quenching occurs when dispersing plasmon modes rise above the particle-hole continuum, extending into the forbidden energy gap that is free from particle-hole excitations. The effect is predicted to be prominent in moiré graphene, where at magic twist-angle values, flat bands feature α≫1. The extinction of Landau damping enhances spatial optical coherence. Speckle-like interference, arising in the presence of disorder scattering, can serve as a telltale signature of undamped plasmons directly accessible in near-field imaging experiments.

Open to: 
General Public