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Edge magnetoplasmons in graphene

Speaker: 
Ivana Petković (SPEC-CEA Saclay, France)
Date: 
Tue, 25/09/2012 - 2:00pm to 3:00pm
Location: 
S13-M01-11 (Physics Conference Room)
Event Type: 
Seminars

Abstract

Edges in two dimensional electron systems (2DES) are central to the quantum Hall effect which depends for its existence on chiral edge currents with vanishing backscattering. But edges also host collective excitations in the form of chiral, globally neutral edge magnetoplasmons (EMP). Much investigated in conventional 2DES, little is known about them in the newly discovered graphene system where electrons obey massless relativistic dynamics. By timing the propagation of narrow wave-packets along the edge of an exfoliated graphene sample on picosecond time scales, we find that the propagation is chiral with low attenuation and the velocity is quantized on the Hall plateaus. We extract the electron drift velocity, which we show to be slightly less than the Fermi velocity, as expected for the abrupt edge of graphene. It is substantially higher than in conventional quantum 2DES, which makes it experimentally accessible. Spatial spread of charge imbalance is shown to be narrower than for conventional soft edged systems.

 

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