Anomalous Landau Levels in Inhomogeneous Fluxes and Emergent Supersymmetry

Abstract

Two-dimensional systems in magnetic fields host rich physics, most notably the quantum Hall effect arising from Landau level quantization. In a broad class of two-dimensional models, flat bands with topologically nontrivial band degeneracies give rise to anomalous Landau level quantization under homogeneous fields. Ascribed to the underlying quantum geometry, these are classified as singular flat bands, exhibiting unusual wavefunction localization, and anomalous quantization of Landau levels. We investigate the response of gapless singular flat bands to inhomogeneous fluxes, bridging continuum and lattice descriptions. Our analysis reveals a mechanism to controllably manipulate the anomalous Landau levels via flux inhomogeneity. We further uncover an emergent supersymmetry in the parameter space where the tower of anomalous Landau levels collapses to zero energy, rendering a lattice analog of the Aharonov-Casher theorem on degenerate zero modes in perpendicular fluxes, with wavefunction localization partly similar to Aharonov-Bohm caging. With the addition of strong correlations, these findings will have implications for realizing exotic topological and charge-ordered phases.