Acoustic double negativity induced by position correlations within a disordered set of monopolar resonators

TL;DR

This paper demonstrates that short-range correlations in a disordered monopolar resonator medium can induce acoustic double negativity, leading to negative refraction, which is unexpected in such systems.

Contribution

It reveals that position correlations in disordered monopolar resonators can produce negative effective parameters and acoustic transparency, expanding understanding of metamaterials.

Findings

Introduction of correlations creates a transparency window.

Negative effective compressibility and density observed.

Negative refraction of ultrasonic waves demonstrated.

Abstract

Using a Multiple Scattering Theory algorithm, we investigate numerically the transmission of ultrasonic waves through a disordered locally resonant metamaterial containing only monopolar resonators. By comparing the cases of a perfectly random medium with its pair correlated counterpart, we show that the introduction of short range correlation can substantially impact the effective parameters of the sample. We report, notably, the opening of an acoustic transparency window in the region of the hybridization band gap. Interestingly, the transparency window is found to be associated with negative values of both effective compressibility and density. Despite this feature being unexpected for a disordered medium of monopolar resonators, we show that it can be fully described analytically and that it gives rise to negative refraction of waves.