CITE.CC academic search helps you expand the influence of your papers.
Abstract
A recent experimental study of the fractional quantum Hall state—a prototypical system exhibiting strong collective quantum behaviour—provided evidence for the existence of unexpected collective modes at a filling factor of 1/3. Fully microscopic calculations now explain these modes as arising from collective excitations within the composite fermion theory. The fractional quantum Hall state1 is a quintessential system for the study of collective quantum behaviour. In such a system, the collective behaviour results in the creation of so-called composite fermions, quasi-particles formed by electrons attached to magnetic flux quanta. Recently, a new collective mode was unexpectedly observed in Raman scattering experiments2 on such a system as it was found to split off from the familiar ‘fundamental’ long-wavelength mode on increase of the wave vector. Here, we present results from extensive theoretical calculations that make a compelling case that this mode corresponds to an excitation of a composite fermion across two Λ levels—effective kinetic energy levels resembling Landau levels for such particles. In addition to explaining why this excitation merges with the fundamental mode in the long-wavelength limit, our theory also provides a good quantitative account of the amount of splitting, and makes several experimentally verifiable predictions.Cite this article
Majumder, D., Mandal, S. & Jain, J. Collective excitations of composite fermions across multiple Λ levels. Nature Phys 5, 403–406 (2009). https://doi.org/10.1038/nphys1275 