Spin excitation spectra of integral and fractional quantum Hall systems

Wójs, Arkadiusz; Quinn, John J.

doi:10.1103/physrevb.66.045323

Cited by 34 publications

(45 citation statements)

References 74 publications

(151 reference statements)

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“…9͒ and some not͔. There is a clear similarity between the =1+QE and =1/ 3 + QE spectra, 32 suggesting that also the Heisenberg QHF at =1/ 3 supports skyrmions. However, since =2/ 5 and 2/3 are Ising rather than Heisenberg ferromagnets, the question on the nature of the two-and more-spin-flips excitations here remains open.…”

Section: B More Spin Flipsmentioning

confidence: 67%

Charge-spin excitations of the Ising-type fractional quantum Hall ferromagnets

et al. 2009

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We study the low-lying excitations from the fractional quantum Hall states at filling factors 2/3 and 2/5 and argue that the charge-carrying excitations involve spin flips, and, in particular, possibly more than one. Energies obtained by exact diagonalization and transport activation gaps measured over a wide range of magnetic fields are invoked. We discuss the relevance of the noninteracting composite-fermion picture where both fractions correspond to the same filling factor 2 of the composite fermions. DOI: 10.1103/PhysRevB.80.045407 PACS number͑s͒: 73.43.Ϫf, 75.10.Lp, 73.63.Ϫb In Jain's composite-fermion ͑CF͒ picture, 1 incompressible electron states 2 of the fractional quantum Hall ͑FQH͒ effect 3 form pairs corresponding to the same magnitude of the effective magnetic field B ‫ء‬ acting on the CFs. For example, the distinct FQH states at Landau-level ͑LL͒ filling factors =2/ 5 and 2/3 both correspond to two effective LLs completely filled with the CFs, i.e., to the same effective filling factor ‫ء‬ = 2. These states are distinguished by the orientation of B ‫ء‬ with respect to the real magnetic field acting on the electrons. Some properties of these FQH systems are known and can be understood using the mentioned analogy, for instance the Ising-like transition between ground states ͑GS͒ of different magnetization ͑paramagnetic and ferromagnetic͒, 4,5 some other properties are known but the applicability of the composite-fermion picture is not established, like the existence of a half-polarized ground state 6 ͑whose microscopic origin is still debated͒, 7 and some are not explored yet. It was found in a previous study that the measured gaps for =2/ 5 and 2/3 showed different dependences on magnetic field which was interpreted using different g factors for CFs. 8 However, no detailed calculations were undertaken at that time to understand this observed effect. Exactdiagonalization ͑ED͒ studies could clarify the underlying physics. Can charged excitations exist at these filling factors that carry large spin? If so, how far can these excitations be understood using the CF picture? Such excitations, identified as skyrmions, 9 do exist at filling factor 1 and its CF counterpart =1/ 3 which are Heisenberg-like quantum Hall ferromagnets ͑QHF͒, 10 as shown by numerous experimental and theoretical arguments. 11 They may be viewed as an extension of the idea of FQH quasiparticles involving single spin flip. 12 Systems at filling factors 2/5 and 2/3 define a wider field for research, first because of their two possible GS ͑polarized and spin singlet͒, second because there are no analytical models for large spin quasiparticles such as skyrmions, and also because the similarity between 2/5 and 2/3 on the CF level can be tested. In this paper, we investigate the lowest excited states of these ‫ء‬ = 2 systems and present arguments for the spin flips being involved.We begin by a recapitulation of known properties for = 2 in Sec. I. The following section first deals with how this knowledge is transferred to the fractional ...

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Section: B More Spin Flipsmentioning

confidence: 67%

Charge-spin excitations of the Ising-type fractional quantum Hall ferromagnets

et al. 2009

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“…8,11,30,31 However, it must be carefully noticed that the predicted absence of Laughlin correlations does not preclude the FQH effect itself, only a microscopic origin of the effect attributable to Laughlin correlations. It should also be realized that immediate application of the CF model without studying the interactions between the relevant particles (electrons, QP's, etc.)…”

Section: Pseudopotentials Laughlin Correlations and The Composimentioning

confidence: 99%

Fractional quantum Hall states of clustered composite fermions

2004

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The energy spectra and wavefunctions of up to 14 interacting quasielectrons (QE's) in the Laughlin ν = 1 3 fractional quantum Hall (FQH) state are investigated using exact numerical diagonalization. It is shown that at sufficiently high density the QE's form pairs or larger clusters. This behavior, opposite to Laughlin correlations, invalidates the (sometimes invoked) reapplication of the composite fermion picture to the individual QE's. The series of finite-size incompressible ground states are identified at the QE filling factors νQE = 1 2 , 1 3 , 2 3 , corresponding to the electron fillings ν = 3 8 , 4 11 , 5 13 . The equivalent quasihole (QH) states occur at νQH = 1 4 , 1 5 , 2 7 , corresponding to ν = 3 10 , 4 13 , 5 17 . All these six novel FQH states were recently discovered experimentally. Detailed analysis indicates that QE or QH correlations in these states are different from those of well-known FQH electron states (e.g., Laughlin or Moore-Read states), leaving the origin of their incompressibility uncertain. Halperin's idea of Laughlin states of QP pairs is also explored, but is does not seem adequate.

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“…being the analogue of an interband dark triplet X − ) are stable ground states of the system [15,17,25], with infinite lifetimes, not limited by radiative recombination.…”

Section: Spin Waves and Skyrmionsmentioning

confidence: 99%

“…Some of the results have been earlier published in Refs. [21][22][23][24][25][26], but Figs. 1b, 2, 3, and 8 are presented here for the first time.…”

Section: A Wójsmentioning

confidence: 99%

“…The energies E will be shown as a function of the conserved orbital (L and L z ) and spin (S and S z ) quantum numbers. To interpret the results obtained in the spherical geometry for the infinite planar system, L and L z must be appropriately translated into the corresponding planar quantities [22,25]. For example, for the (charge or spin) wave eigenstates that carry no net charge, angular momentum L must be replaced by wave vector k = L/R, while for the eigenstates corresponding to charged excitations L and L z are connected with planar angular momentum projection M and its center-of-mass component M CM .…”

Section: Modelmentioning

confidence: 99%

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Photoluminescence of Charged Excitons in Fractional Quantum Hall Systems

Wójs

2004

Acta Phys. Pol. A

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Neutral and charged excitonic complexes formed in integral and fractional quantum Hall systems are discussed. They are bound states of a small number of charged quasiparticles (e.g., conduction electrons and valence holes, reversed-spin electrons and spin holes, Laughlin quasielectrons and quasiholes, composite fermions) that occur in an electron system under specific conditions (electron density, well width, electric and magnetic fields, etc.). The examples are interband neutral and charged excitons, "anyon excitons", spin waves, skyrmions, and "skyrmion excitons". Their possible decay processes include radiative recombination, experimentally observed in photoluminescence or far infrared emission, or spin transitions, important in the context of nuclear spin relaxation.

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Spin excitation spectra of integral and fractional quantum Hall systems

Cited by 34 publications

References 74 publications

Charge-spin excitations of the Ising-type fractional quantum Hall ferromagnets

Charge-spin excitations of the Ising-type fractional quantum Hall ferromagnets

Fractional quantum Hall states of clustered composite fermions

Photoluminescence of Charged Excitons in Fractional Quantum Hall Systems

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