Topological edge states in concave hexagonal gyroscope phononic crystals

Area of Science:

• Acoustics
• Condensed Matter Physics
• Materials Science

Background:

• Topological acoustics leverages unique wave phenomena in engineered materials.
• Gyroscopic elements offer novel ways to tune material properties dynamically.

Purpose of the Study:

• To propose and analyze a gyroscopic phononic crystal (GPC) with a concave hexagonal lattice.
• To investigate the mechanisms for opening band gaps and generating topological edge states in GPCs.
• To explore the tunability of GPC properties via gyroscope torque and rotation velocity.

Main Methods:

• Analysis of bandgap characteristics in a GPC structure with torsional wave propagation.
• Investigation of symmetry breaking (structural and time-reversal) to open band gaps.
• Supercell analysis to study wave propagation at topological interfaces.

Main Results:

• Two band gaps were opened by breaking structural and time-reversal symmetry, hosting topological edge states.
• Gyroscope torque and rotation velocity were shown to influence band inversion and valley Hall edge states.
• Robustness of topological edge states to defects was demonstrated.

Conclusions:

• GPCs provide a novel platform for topological acoustics with tunable properties.
• The proposed GPC design exhibits robust topological edge states with distinct directivity.
• This research opens new avenues for acoustic wave manipulation and topological phononics.