Unbounded Tellegen Response in Media with Multiple Resonances

TL;DR

This paper demonstrates that in media with multiple close resonances, the traditional restriction on the Tellegen coefficient is lifted, enabling a giant nonreciprocal magneto-electric response in photonics and condensed matter.

Contribution

The paper provides a theoretical foundation showing that the restriction on the Tellegen coefficient can be overcome in media with multiple resonances, leading to a giant response.

Findings

Restriction on Tellegen coefficient is lifted in resonant media.

Giant Tellegen response is theoretically possible in such media.

Provides a new foundation for nonreciprocal photonic and condensed matter applications.

Abstract

Tellegen response is a special type of nonreciprocal magneto-electric coupling which long remained elusive in photonics and extremely weak in condensed matter. It is widely accepted that the Tellegen coefficient is restricted by $\chi^2<\varepsilon\mu$, where $\varepsilon$ and $\mu$ are permittivity and permeability of the material. Here, we demonstrate that this restriction is lifted in the medium with several close resonances, which provides a theoretical foundation for giant Tellegen response.