Magnetic field induced transition in a wide parabolic well superimposed with superlattice

TL;DR

This paper investigates how magnetic fields induce a transition in electron distribution within a parabolic quantum well superimposed with a superlattice, revealing a shift to layered states and fractional quantum Hall phenomena.

Contribution

It demonstrates a magnetic field-driven transition from delocalized to layered electron states in a disordered superlattice within a parabolic quantum well, highlighting electron localization and FQH state formation.

Findings

Transition occurs at Landau filling factor ~3

Observation of strong fractional quantum Hall states

Enhanced Hall resistance slope indicating state change

Abstract

We study a $Al_{x}Ga_{x-1}As$ parabolic quantum wells (PQW) with $GaAs/Al_{x}Ga_{x-1}As$ square superlattice. The magnetotransport in PQW with intentionally disordered short-period superlattice reveals a surprising transition from electrons distribution over whole parabolic well to independent-layer states with unequal density. The transition occurs in the perpendicular magnetic field at Landau filling factor $\nu\approx3$ and is signaled by the appearance of the strong and developing fractional quantum Hall (FQH) states and by the enhanced slope of the Hall resistance. We attribute the transition to the possible electron localization in the x-y plane inside the lateral wells, and formation of the FQH states in the central well of the superlattice, driven by electron-electron interaction.