Dissipation in finite systems: Semiconductor NEMS, graphene NEMS, and metallic nanoparticles

TL;DR

This thesis investigates dissipation mechanisms in mesoscopic systems including semiconductor NEMS, graphene NEMS, and metallic nanoparticles, revealing how environmental interactions affect their vibrational and plasmonic properties.

Contribution

It provides a comparative analysis of dissipation effects across different nanoscale systems, highlighting the limitations of existing models and identifying key factors influencing quality factors.

Findings

Surface friction limits Q-factor in semiconductor NEMS at low temperatures

Multiple damping mechanisms affect graphene nanoresonators' vibrational modes

Theoretical models of surface plasmon dynamics have specific validity limits

Abstract

This thesis studies three kinds of mesoscopic systems and how one of their collective degrees of freedom is affected by a dissipative environment: a)Nanoelectromechanical systems based on semiconductor materials, and how surface friction processes limit the quality factor of their vibrational eigenmodes at low temperatures, causing as well a frequency shift; b)Graphene - based nanoresonators, and several damping mechanisms limiting the quality factor of its fundamental bending (flexural) eigenmode, and c)The dissipative dynamics of the surface plasmon created in a metallic nanocluster by a laser pulse, discussing the validity and limitations of a very common theoretical model used for its description.