Low-loss bulk and edge plasmons in graphene heterostructures – a theoretical study

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• Alessandro Principi (Manchester)
• Thursday 14 June 2018, 13:45-15:00
• Theory Library.

If you have a question about this talk, please contact Mike Gunn.

Graphene plasmons have recently attracted a great deal of attention because of their tunability, long lifetime, and high degree of field confinement in the vertical direction, potentially enabling new classes of devices for deep subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches.

We theoretically investigate the properties of graphene plasmons in the bulk and at the edge. For bulk modes, we find that at room temperature the scattering against graphene’s acoustic phonons is the dominant limiting factor for hBN/G/hBN stacks. We also study the plasmons of a graphene sheet deposited on a metal, in the regime in which metal bands do not hybridize with massless Dirac fermion bands. The graphene plasmon dispersion is found to be acoustic and pushed down in energy towards the upper boundary of the intraband graphene particle-hole continuum, thereby strongly enhancing the vertical confinement of these excitations. Landau damping of such acoustic plasmons due to particle-hole excitations in the metal gate is found to be surprisingly weak.

At the edge, the presence of strain fields induces novel charged counter-propagating acoustic edge modes. In the limit of large pseudomagnetic fields, each of them involves oscillations of only one of the two electronic components. Furthermore, we show that new chiral valley-polarized second-sound collective modes can propagate along the edges of novel materials with non-trivial Berry curvatures.

This talk is part of the Theoretical Physics Seminars series.

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