Defects may help scientists understand the exotic physics of topology

Science Daily  January 22, 2021
Researchers at the University of Illinois engineered metamaterials to include defects to show that defects and structural deformations can provide insights into a real material’s hidden topological features. They experimentally demonstrated that disclination defects can robustly trap fractional charges in topological crystalline insulators (TCI) metamaterials, and the trapped charge can indicate non-trivial, higher-order crystalline topology even in the absence of any spectral signatures. They uncovered a connection between the trapped charge and the existence of topological bound states localized at these defects. By testing the robustness of these topological features when the protective crystalline symmetry was broken, they found that a single robust bound state can be localized at each disclination alongside the fractional charge. The results conclusively showed that disclination defects in TCIs can strongly trap fractional charges as well as topological bound states and demonstrated the primacy of fractional charge as a probe of crystalline topology…read more. TECHNICAL ARTICLE

Measurement of trapped fractional mode density. Credit: Nature volume 589, pages376–380(2021)

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