Effect of Landau Level Mixing for Electrons in Random Magnetic Field

TL;DR

This paper investigates how Landau level mixing affects the energy spectrum of electrons in a random magnetic field, revealing that localized states shift upward with decreasing B_0, unlike extended states, and highlighting the impact of Zeeman effects.

Contribution

It introduces an effective Hamiltonian approach to analyze Landau-level mixing effects, showing that localized and extended states respond differently to magnetic disorder.

Findings

Localized electron levels shift upward as B_0 decreases

Extended states remain static despite magnetic disorder

Zeeman term significantly affects low-lying Landau levels

Abstract

An effective Hamiltonian approach is used to study the effect of Landau-level mixing on the energy spectrum of electrons in a smooth but random magnetic field B(r) with a finite uniform component B_0. It is found that, as opposed to electrostatic disorder, the energy levels of localized electrons shift upward with a rate of order O(1/B_0) when B_0 is decreased, while the extended states remain static at the same order. Therefore, there is no indication that the extended states will float out of the Fermi energy and induce a metal-insulator transition as the magnetic disorder is increased. We also find that the Zeeman term may have significant effect on the spectral shift of low-lying Landau levels.