Aleksandra Nelson (UZH)
We enrich the notions of stable and fragile topology by introducing delicate topological insulators: band structures possessing topological invariants that can be trivialized through an addition of a trivial conduction band. We find that although delicate topological insulators are Wannier representable with exponentially-localized symmetry-preserving Wannier functions, they can possess a different type of obstruction to an atomic limit. Namely, impossibility to localize all Wannier functions to one unit cell, i.e. multicellularity. In this talk, I will explain the concepts of delicacy and multicellularity on a toy-example and discuss their observable consequences.
Aleksandra Nelson (UZH) Titus Neupert (University of Zurich) Tomáš Bzdušek (Paul Scherrer Institut) Aris Alexandradinata (University of Illinois at Urbana-Champaign)