2020/07/30 by Lingling Song, Huanhuan Yang, Yunshan Cao +1 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.other
paper · pdf · doi:10.1021/acs.nanolett.0c03049
published as Nano Lett. 20, 7566 (2020)
arxiv created 2020/07/30 · arxiv updated 2020/11/17
Higher-order topological insulator (HOTI) represents a new phase of matter, the characterization of which goes beyond the conventional bulk-boundary correspondence and is attracting significant attention by the broad community. Using a square-root operation, it has been suggested that a square-root HOTI may emerge in a hybrid honeycomb-kagome lattice. Here, we report the first experimental realization of the square-root HOTI in topological LC circuits. We show theoretically and experimentally that the square-root HOTI inherits the feature of wave function from its parent, with corner states pinned to non-zero energies. The topological feature is fully characterized by the bulk polarization. To directly measure the finite-energy corner modes, we introduce extra grounded inductors to each node. Our results experimentally substantiate the emerging square-root HOTI and pave the way to realizing exotic topological phases that are challenging to observe in condensed matter physics.