Abstract
Second-order topological insulators are crystalline insulators with a gapped bulk and gapped crystalline boundaries, but with topologically protected gapless states at the intersection of two boundaries. Without further spatial symmetries, five of the ten Altland-Zirnbauer symmetry classes allow for the existence of such second-order topological insulators in two and three dimensions. We show that reflection symmetry can be employed to systematically generate examples of second-order topological insulators and superconductors, although the topologically protected states at corners (in two dimensions) or at crystal edges (in three dimensions) continue to exist if reflection symmetry is broken. A three-dimensional second-order topological insulator with broken time-reversal symmetry shows a Hall conductance quantized in units of .
- Received 12 August 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.246401
© 2017 American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Topological Insulators Turn a Corner
Published 11 December 2017
Theorists have discovered topological insulators that are insulating in their interior and on their surfaces but have conducting channels at corners or along edges.
See more in Physics