Optical Tellegen metamaterial with spontaneous magnetization

Area of Science:

• Condensed matter physics
• Metamaterials science
• Electromagnetism

Background:

• The nonreciprocal magnetoelectric effect (Tellegen effect) is crucial for fundamental physics and applications like magnetless isolators.
• Existing metamaterials often require external magnetic bias or lack isotropic responses.

Purpose of the Study:

• To propose a three-dimensional metamaterial with an isotropic and resonant Tellegen response in the visible frequency range.
• To demonstrate a metamaterial that operates without external magnetic bias, utilizing spontaneous magnetization.

Main Methods:

• Fabrication of a 3D metamaterial composed of randomly oriented bi-material nanocylinders (ferromagnet and high-permittivity dielectric) in a host medium.
• Tuning nanocylinder composition to achieve magnetic Mie-type resonance.
• Investigating the use of magnetic Weyl semimetals to enhance the magnetoelectric effect.

Main Results:

• Demonstrated an isotropic and resonant Tellegen response in the visible spectrum.
• Achieved operation based on spontaneous magnetization, eliminating the need for external magnetic bias.
• Showcased a potential for a giant bulk effective magnetoelectric effect, significantly exceeding natural materials.

Conclusions:

• The proposed metamaterial offers a promising platform for realizing the Tellegen effect in the visible range without external magnetic fields.
• Integration with magnetic Weyl semimetals can lead to unprecedented magnetoelectric properties.
• This work paves the way for advanced optical devices and fundamental physics explorations.