Optical Tellegen metamaterial with spontaneous magnetization

TL;DR

This paper introduces a 3D optical metamaterial exhibiting spontaneous magnetoelectric effects without external magnetic bias, achieved through nanocylinders with magnetic and dielectric properties, promising groundbreaking applications in fundamental and applied physics.

Contribution

The paper presents a novel isotropic, resonant Tellegen metamaterial operating in the visible range, utilizing spontaneously magnetized nanocylinders, and demonstrates giant magnetoelectric effects surpassing natural materials.

Findings

Achieves isotropic Tellegen response in visible frequencies

Demonstrates giant bulk magnetoelectric effect exceeding natural materials

Operates without external magnetic bias using spontaneous magnetization

Abstract

The nonreciprocal magnetoelectric effect, also known as the Tellegen effect, promises a number of groundbreaking phenomena connected to fundamental (e.g., electrodynamics of axion and relativistic matter) and applied physics (e.g., magnetless isolators). We propose a three-dimensional metamaterial with an isotropic and resonant Tellegen response in the visible frequency range. The metamaterial is formed by randomly oriented bi-material nanocylinders in a host medium. Each nanocylinder consists of a ferromagnet in a single-domain magnetic state and a high-permittivity dielectric operating near the magnetic Mie-type resonance. The proposed metamaterial requires no external magnetic bias and operates on the spontaneous magnetization of the nanocylinders. By leveraging the emerging magnetic Weyl semimetals, we further show how a giant bulk effective magnetoelectric effect can be achieved in a proposed metamaterial, exceeding that of natural materials by almost four orders of magnitude.