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Lei Shan Thesis Defense 07/30/2018

Thesis Defense

Lei Shan Monday, July 30, 2018 at 2 PM (334 JFB)

Title: Plasmonic Excitonic Effect in Restricted Geometries.

In this talk, I will discuss many-body depolarization and excitonic effects in quantum wires and nanotubes. One-dimensional electron system is distinctly different than high dimensional counterparts due to the degeneracy of Fermi surface. Such system is commonly described by Luttinger liquid in which elementary excitations are noninteracting bosons if umklapp term and backscattering are ignored. Metallic nanotubes as rolled-up strips of graphene are regarded as ideal materials in testing Luttinger liquid effects. Depolarization effect in nanotubes stems from the redistribution of conduction electrons around the circumference, which can be explained in the frame of Random Phase Approximation(RPA). However, such simple picture breaks down if Luttinger liquid effect is considered. Absorption rate near the threshold yields more singular result which goes beyond the prediction from RPA. Furthermore, exciton as a bound state of an electron and a hole is believed not existing in metals. However, by the virtue of weak screening in 1D, it is possible to observe exciton in metallic nanotubes. We calculated corresponding binding energy and decay rate of excitons analytically.

Publications:

[1]. L. Shan, M. Agarwal, and E. G. Mishchenko, “Binding Energy and Lifetime of Excitons in Metallic Nanotubes”, http://arxiv.org/abs/1807.03962

[2]. Lei Shan and E. G. Mishchenko, “Breakdown of Classical Electrostatics in the Depolarization of Quantum Wires and Nanotubes”, Phys. Rev. B 96, 195441 (2017).

[3]. Lei Shan, E. G. Mishchenko, and M. E. Raikh, “Plasmon Spectrum andPlasmon-Mediated Energy Transfer in a Multiconnected Geometry,” Phys. Rev. B 93, 085435(2016).

Last Updated: 12/21/18