Bulk-disclination correspondence in topological crystalline insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Photonics

Background:

• Topological crystalline materials exhibit abundant topological phases.
• Bulk-edge correspondence is insufficient for classifying diverse topological crystalline phases.
• Disclinations, crystallographic defects, are theoretically proposed probes of crystalline topology.

Purpose of the Study:

• To experimentally demonstrate bulk-disclination correspondence.
• To explore disclinations as probes for topological crystalline materials.
• To investigate fractional spectral charge and bound states at disclinations.

Main Methods:

• Utilized reconfigurable photonic crystals as photonic topological crystalline insulators (TCIs) with higher-order topology.
• Employed pump-probe and near-field detection measurements.
• Observed spectral charge and bound states at disclinations.

Main Results:

• Experimental evidence of bulk-disclination correspondence was observed.
• Fractional spectral charge and robust bound states emerged at disclinations in the TCI phase.
• These phenomena vanished in the trivial phase, confirming their topological origin.

Conclusions:

• The study experimentally validates bulk-disclination correspondence.
• Disclinations serve as effective probes for topological crystalline insulators.
• This finding provides a new paradigm for exploring topological materials.