A theory of electrodynamic response for bounded metals: surface capacitive effects

Deng, Hai-Yao ORCID: https://orcid.org/0000-0001-6065-483X 2020. A theory of electrodynamic response for bounded metals: surface capacitive effects. Annals of Physics 418 , 168204. 10.1016/j.aop.2020.168204

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Abstract

We report a general macroscopic theory for the electrodynamic response of semi-infinite metals (SIMs). The theory includes the hitherto overlooked capacitive effects due to the finite spatial extension of a surface. The basic structure of this theory is independent of the particulars of electron dynamics. Analytical expressions have been obtained of the charge density–density response function, which is naturally parsed into two parts. One of them represents a bulk property while the other a pure surface property. We apply the theory to study the responses according to several electronic dynamics models and provide a unified view of their validity and limitations. The models studied include the local dielectric model (DM), the dispersive hydrodynamic model (HDM) and specular reflection model (SRM), as well as the less common semi-classical model (SCM) based on Boltzmann’s transport equation. We show that, in terms of their basic equations, the SRM is an extension of the HDM, just as the HDM is an extension of the DM. The SCM improves over the SRM critically through the inclusion of translation symmetry breaking and surface roughness effects. We then employ the response function to evaluate the so-called dynamical structure factor, which plays an important role in particle scattering. As expected, this factor reveals a peak due to the excitation of surface plasma waves (SPWs). Surprisingly, however, the peak is shown to be considerably sharper in the SCM than in other models, indicating an incipient instability of the system according to this model. We also study the distribution of charges induced by a charged particle grazing over a SIM surface at constant speed. This distribution is shown to contain model-specific features that are of immediate experimental interest. This work is expected to find broad applications in optics, plasmonics and other areas such as electron energy loss spectroscopy and accelerator design.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	Elsevier Masson
ISSN:	0003-4916
Date of First Compliant Deposit:	27 May 2020
Date of Acceptance:	14 May 2020
Last Modified:	06 Nov 2023 17:00
URI:	https://orca.cardiff.ac.uk/id/eprint/131946

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