paper

Quantization of fractional corner charge in -symmetric higher-order topological crystalline insulators

arXiv:1809.02142 · doi:10.1103/PhysRevB.99.245151

Abstract

In the presence of crystalline symmetries, certain topological insulators present a filling anomaly: a mismatch between the number of electrons in an energy band and the number of electrons required for charge neutrality. In this paper, we show that a filling anomaly can arise when corners are introduced in -symmetric crystalline insulators with vanishing polarization, having as consequence the existence of corner-localized charges quantized in multiples of . We characterize the existence of this charge systematically and build topological indices that relate the symmetry representations of the occupied energy bands of a crystal to the quanta of fractional charge robustly localized at its corners. When an additional chiral symmetry is present, corner charges are accompanied by zero-energy corner-localized states. We show the application of our indices in a number of atomic and fragile topological insulators and discuss the role of fractional charges bound to disclinations as bulk probes for these crystalline phases.

Main Text: 13 pages, 7 figures. Supp. Info: 20 pages, 23 figures

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