Redistributing Chern numbers of Landau subbands: tight-binding electrons under staggered-modulated magnetic fields

TL;DR

This paper studies how staggered-modulated magnetic fields affect the Chern numbers of Landau subbands in a square lattice, revealing a robust redistribution that causes quantized Hall conductance to change abruptly, offering a potential experimental probe.

Contribution

It demonstrates a novel redistribution of Chern numbers in Landau subbands under staggered magnetic flux modulation, leading to quantized Hall conductance transitions.

Findings

Chern numbers are redistributed between neighboring Landau subbands.

Quantized Hall conductance exhibits a direct transition of ^2/h at critical fillings.

The effect is robust against weak disorder and can serve as an experimental probe.

Abstract

We investigate the magneto-transport properties of electrons on a square lattice under a magnetic field with the alternate flux strength $\phi\pm\Delta\phi$ in neighboring plaquettes. A new peculiar behavior of the Hall conductance has been found and is robust against weak disorder: if $\phi={p\over{2N}}\times{2\pi}$ ($p$ and $2N$ are coprime integers) is fixed, the Chern numbers of Landau subbands will be redistributed between neighboring pairs and hence the total quantized Hall conductance exhibits a direct transition by $\pm{N}e^2/h$ at critical fillings when $\Delta\phi$ is increased from 0 up to a critical value $\Delta\phi_c$. This effect can be an experimental probe of the staggered-flux phase.