WJ Stewart | Searcharxiv

arXiv2025

Extremely Low Frequency Plasmons in Metallic Microstructures

The plasmon is a well established collective excitation of metals in the visible and near UV but at much lower frequencies dissipation destroys all trace of the plasmon and typical Drude behaviour sets in. We propose a mechanism for depression of the plasma frequency into the far infra red or even GHz band: periodic structures build of very thin wires dilute the average concentration of electrons and considerably enhance the effective electron mass through self-inductance. Computations replicate the key features and confirm our analytic theory. The new structure has novel properties not observed before in the GHz band, including some possible impact on superconducting properties.

cond-mat.mes-hall↗

arXiv2025

Magnetism from Conductors, and Enhanced Non-Linear Phenomena

We show that microstructures built from non-magnetic conducting sheets exhibit an effective magnetic permeability, /mu_meff, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of /mu_meff. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly non-linear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states

physics.app-ph↗