Condensed Matter Physics Seminar: Karolina Slovik

Abstract:
Low-dimensional materials like graphene nanoflakes can sustain plasmonic excitations. As
such, they can be treated as tunable plasmonic nanoantennas and can be exploited to
modify the optical properties of neighbouring atomic systems. However, the tight
confinement of graphene plasmons requires the atomic system to be positioned extremely
close to capitalise on the plasmonic enhancement. This unlocks the possibility of electron
tunnelling between the atomic system and graphene nanoantenna, and thus, a back-action
of the atomic system which can modify the optical response of the flake.
In our work, we investigate the interplay of graphene nanoantennas with adatoms playing
the roles of quantum emitters. We characterise how the co-existence of optical and
electronic coupling impacts basic phenomena such as coherent coupling of the system
with light or Purcell fluorescence enhancement. The analysis reveals two distinct
interaction regimes depending on the adatom position. Furthermore, we propose an
energy-based plasmonicity index (EPI) to redefine plasmon excitation in atomistic-sized
systems. It offers a novel perspective that aligns with energy-space coherence dynamics,
providing a complementary approach to existing classifications and enhancing our
understanding of plasmonicity in nanostructured materials.