Moiré-Driven Topological Transitions and Extreme Anisotropy in Elastic Metasurfaces.

Area of Science:

• Physics
• Materials Science
• Metasurfaces

Background:

• Twistronics in 2D materials reveals phenomena like superconductivity and topological phases.
• Current limitations include fabrication challenges and restricted control over geometry and twist angle in stacked multilayers.

Purpose of the Study:

• To extend twistronics principles to macroscopic, reconfigurable elastic metasurfaces.
• To demonstrate tailored anisotropy and tunable wave properties using twist angle variations in a single-layer system.

Main Methods:

• Utilized LEGO pillar resonators to create macroscopic elastic metasurfaces.
• Engineered quasi-periodic moiré patterns by controlling twist angles between interleaved pillar lattices.
• Investigated topological transitions in isofrequency contours.

Main Results:

• Achieved highly tailored anisotropy in a single-layer metasurface through controlled twist angles.
• Demonstrated strong tunability of highly directional waves.
• Observed topological transitions driven by moiré patterns.

Conclusions:

• Twistronics and moiré physics phenomena can be translated to single-layer metasurface platforms.
• Offers a practical route for observing extreme wave phenomena in classical and quantum settings.
• Eliminates the need for multilayered fabrication.