Effective material parameter retrieval for thin sheets: theory and application to graphene, thin silver films, and single-layer metamaterials

TL;DR

This paper introduces a retrieval method for effective material parameters of thin-film structures, using scattering parameters to determine sheet conductivity, with applications to graphene, silver films, and metamaterials.

Contribution

The paper presents a novel sheet retrieval method for thin-film structures that accounts for magnetic sheet currents, improving parameter extraction accuracy.

Findings

Accurately determines effective sheet conductivity of thin silver films.

Validates the method by comparing with graphene's sheet conductivity.

Demonstrates applicability to cut-wire metamaterials with electric dipole resonance.

Abstract

An important tool in the field of metamaterials is the extraction of effective material parameters from simulated or measured scattering parameters of a sample. Here we discuss a retrieval method for thin-film structures that can be approximated by a two-dimensional scattering sheet. We determine the effective sheet conductivity from the scattering parameters and we point out the importance of the magnetic sheet current to avoid an overdetermined inversion problem. Subsequently, we present two applications of the sheet retrieval method. First, we determine the effective sheet conductivity of thin silver films and we compare the resulting conductivities with the sheet conductivity of graphene. Second, we apply the method to a cut-wire metamaterial with an electric dipole resonance. The method is valid for thin-film structures such as two-dimensional metamaterials and frequency-selective surfaces and can be easily generalized for anisotropic or chiral media.