CMSP Series @ICTP Stasi Room Thursday 31 May 11am - R. ASGARI

[CM Section]

ICTP Seminar Series in Condensed Matter and Statistical Physics
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Thursday 31 May at 11:00 a.m.

Luigi Stasi Seminar Room, first floor, ICTP Leonardo building
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Speaker: Reza ASGARI (IPM, Tehran, Iran)

Title:Quantum Non-Local Effects in Graphene Plasmonics

Abstract:
Plasmon modes represent a second kind of possible elementary
excitation for the Fermi liquid. Basically, plasmon modes involve a
cooperative motion of the system, governed by the global interaction
between the charge carriers. Plasmon modes in two-dimensional
electron liquids illustrate a long-wavelength dispersion that can be
captured by classical equations of motion. The dispersion, however,
departs from its classical value, becoming sensitive to quantum effects,
by increasing the plasmon momentum.

The response of electron systems to electrodynamic fields that change
rapidly in space is endowed by unique features, including an exquisite
spatial nonlocality. This can reveal much about the materials’ electronic
structure that is invisible in standard probes that use gradually varying
fields. In this talk, we will start by introducing the plasmonics both 
in single
and double layer graphene and describe the quantum non-locality effects
in graphene plasmonics. Our theory involves three types of nonlocal quantum
effects: single-particle velocity matching, interaction-enhanced Fermi 
velocity,
and interaction-reduced compressibility. The near-field imaging experiments
reveal a parameter-free match with the full quantum description of the 
massless
Dirac electron gas.