Non-Abelian Hopf-Euler insulatorsShow others and affiliations
2024 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 110, no 7, article id 075135Article in journal (Refereed) Published
Abstract [en]
We discuss a class of three-band non-Abelian topological insulators in three dimensions that carry a single bulk Hopf index protected by spatiotemporal (π«π―) inversion symmetry. These phases may also host subdimensional topological invariants given by the Euler characteristic class, resulting in real Hopf-Euler insulators. Such systems naturally realize helical nodal structures in the three-dimensional Brillouin zone, providing a physical manifestation of the linking number described by the Hopf invariant. We show that, by opening a gap between the valence bands of these systems, one finds a fully-gapped βflagβ phase, which displays a three-band multigap Pontryagin invariant. Unlike the previously reported π«π―-symmetric four-band real Hopf insulator, which hosts a β€ββ€ invariant, these phases are not unitarily equivalent to two copies of a complex two-band Hopf insulator. We show that such uncharted phases can be obtained through dimensional extension of two-dimensional Euler insulators, and that they support (i) an optical bulk integrated circular shift effect quantized by the Hopf invariant, (ii) quantum-geometric breathing in the real-space Wannier functions, and (iii) surface Euler topology on boundaries. Consequently, our findings pave the way for novel experimental realizations of real-space quantum geometry, as these systems may be directly simulated by utilizing synthetic dimensions in metamaterials or ultracold atoms.
Place, publisher, year, edition, pages
American Physical Society (APS) , 2024. Vol. 110, no 7, article id 075135
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-353126DOI: 10.1103/PhysRevB.110.075135ISI: 001296382100002Scopus ID: 2-s2.0-85202436121OAI: oai:DiVA.org:kth-353126DiVA, id: diva2:1897357
Note
QC 20240912
2024-09-122024-09-122024-09-12Bibliographically approved