Evidence of Landau levels and interactions in low-lying excitations of composite fermions at 1/3 <= \nu <= 2/5

TL;DR

This study observes excitation modes in the fractional quantum Hall regime, revealing Landau level structures and interactions of composite fermions through resonant inelastic light scattering, with notable changes at certain filling factors.

Contribution

It provides experimental evidence of Landau levels and interactions in composite fermions at filling factors between 1/3 and 2/5, highlighting the structure and dynamics of these quasiparticles.

Findings

Observation of spin-reversed excitation spectra

Identification of Landau level structures similar to electrons

Detection of abrupt changes in mode energies at specific filling factors

Abstract

Excitation modes in the range $2/5 \geq \nu \geq 1/3$ of the fractional quantum Hall regime are observed by resonant inelastic light scattering. Spectra of spin reversed excitations suggest a structure of lowest spin-split Landau levels of composite fermions that is similar to that of electrons. Spin-flip energies determined from spectra reveal significant composite fermion interactions. The filling factor dependence of mode energies display an abrupt change in the middle of the range when there is partial population of a composite fermion level.