Localized surface plasmons in a Weyl semimetal nanosphere

TL;DR

This paper explores how Weyl semimetals' unique properties modify localized surface plasmon modes in nanospheres, revealing multiple resonances and novel excitation mechanisms due to axion electrodynamics.

Contribution

It provides analytical solutions for plasmon modes in Weyl semimetal nanospheres considering axion effects, highlighting their distinct polarization and resonance characteristics.

Findings

Multiple non-degenerate plasmonic resonances identified

Axion term enables excitation of surface plasmons by transverse electric fields

Modified Fröhlich conditions due to axion effects

Abstract

In this study, we investigate the localized surface plasmon modes of a sub-wavelength spherical nanoparticle composed of a Weyl semimetal, taking into account the axion modification of electrodynamics. We derive analytical solutions for dipole and quadrupole normal modes by employing the quasistatic approximation. The axion term leads to modified Fr\"ohlich conditions, resulting in multiple non-degenerate plasmonic resonances with distinct polarization dependencies. In contrast to isotropic conventional metals, the magnetoelectric properties of Weyl semimetals enable an incident electromagnetic field, with the electric field transverse to the surface of the sphere, to excite a localized surface plasmon.