delicate-topology

Delicate topology protected by rotation symmetry: Crystalline Hopf insulators and beyond

Pontrjagin's seminal topological classification of two-band Hamiltonians in three momentum dimensions is hereby enriched with the inclusion of a crystallographic rotational symmetry. The enrichment is attributed to a new topological invariant which …

Delicate topological insulators: a new world of phases between trivial and fragile

Topological band theory studies the behavior of non-interacting electrons in solids that is protected by topological invariants and is therefore robust against system perturbations. Among many topics that are important for characterizing topological …

Theorists discover new paradigm of topological band structures

After the experimental discovery of topological insulators, the notion of what actually constitutes a topological band insulator has been refined in many ways. In their recent work, Aleksandra Nelson, Titus Neupert, Tomáš Bzdušek and Aris Alexandradinata extend the paradigm of topological insulators to areas which were previously thought to contain only trivial insulators.

Multicellularity of delicate topological insulators

Being Wannierizable is not the end of the story for topological insulators. We introduce a family of topological insulators that would be considered trivial in the paradigm set by the tenfold way, topological quantum chemistry, and the method of …

Geometric approach to fragile topology beyond symmetry indicators

We present a framework to systematically address topological phases when finer partitionings of bands are taken into account, rather than only considering the two subspaces spanned by valence and conduction bands. Focusing on …