Tracking Valley Topology with Synthetic Weyl Paths

Area of Science:

• Acoustic Metamaterials
• Condensed Matter Physics
• Topological Physics

Background:

• Topological valley transport in classical metacrystals is a growing field, inspired by valleytronics.
• Current interpretations using valley Chern numbers are limited to small band gaps.
• A new method is needed to track valley topology in classical systems.

Purpose of the Study:

• To propose a novel approach for visualizing and tracking topological valley transport in classical systems.
• To construct Weyl points in synthetic 3D momentum space using acoustic metacrystals.
• To connect 2D valley topology to quantized topological charges in 3D Weyl crystals.

Main Methods:

• Utilizing controllable acoustic metacrystals.
• Introducing a rotation angle as an extra structural parameter to create Weyl points.
• Analyzing 3D Weyl crystal properties, including surface arcs and chiral surface states.

Main Results:

• Successfully constructed Weyl points in synthetic 3D momentum space.
• Demonstrated that 2D valley-projected band topology can be tracked by quantized topological charge in the 3D Weyl crystal.
• Observed open surface arcs connecting synthetic Weyl points and gapless chiral surface states.

Conclusions:

• The proposed method provides a new perspective for understanding topological valley physics.
• Experimental verification confirms theoretical predictions.
• Findings contribute to the advancement of topological valley physics in classical systems.