Nov 10, 2025
Research: Quantum Hall Effect without Chern Bands
Panel (a): Underlying trivial band structure. Panel (b): Hall conductance without disorder (W = 0) and at a finite amplitude W = 1.5 of the disorder potential.
The quantum Hall effect was originally observed in a two-dimensional electron gas forming Landau levels when exposed to a strong perpendicular magnetic field and was later generalized to Chern insulators without net magnetization. However, this setting still requires topological bands with non-zero Chern number. Researchers at TU Dresden have now further extended the realm of the quantum Hall effect to band structures that are completely trivial by conventional measures (zero Chern number of all bands), but exhibit mutually compensating and energetically separated Berry fluxes. Then, adding disorder creates a mobility gap that immediately nudges the system into a quantum Hall phase from an extended critical regime obtained by placing the Fermi energy within a broad window inside a trivial band. This effect may be seen as a natural integer rounding mechanism occurring at the onset of disorder. The results are corroborated by extensive numerical simulations.
B. Michen, J. C. Budich,
Quantum Hall Effect without Chern Bands,
Phys. Rev. Lett. 135, 186603 (2025) (arXiv)