Bound states at partial dislocation defects in multipole higher-order topological insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Physics

Background:

• The bulk-boundary correspondence is a key feature of topological insulators, linking bulk topological properties to boundary states.
• In crystalline materials, topological boundary states can be obscured or absent, especially in higher-order topological insulators.
• Partial dislocations, exotic defects of translation symmetry, were theoretically proposed to host topological modes.

Purpose of the Study:

• To experimentally observe and characterize topological modes induced by partial dislocations in insulators.
• To investigate the role of partial dislocations in multipole higher-order topological insulators.
• To demonstrate the utility of circuit-based resonator arrays for studying these phenomena.

Main Methods:

• Experimental realization of 2D and 3D insulator models using circuit-based resonator arrays.
• Engineering of stacking faults and partial dislocations within these arrays.
• Characterization of topological modes localized at these defects.

Main Results:

• Direct experimental observation of gapless topological modes trapped at partial dislocations.
• Demonstration that these modes are distinct from boundary artifacts and are robust.
• Successful implementation in multipole higher-order topological insulators, which are insensitive to full dislocations.

Conclusions:

• Partial dislocations can indeed induce and host gapless topological modes in insulating materials.
• Circuit-based resonator arrays provide a versatile platform for exploring defect-induced topology.
• This work expands the understanding of topological phenomena beyond traditional bulk-boundary correspondence.