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Eisenstein, Elizabeth L.; Lewis, Roy; Lindsay, Jack; Weyr, Thomas; Osburn, Charles B.; Egan, Robert W.

doi:10.1080/10948007909488737

Cited by 10 publications

(10 citation statements)

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“…The theoretical predictions obtained above from our calculations are in good overall agreement with the experiments of Eisenstein et al [5,11]. For example, the peak position obtained in our simple model is quite close to the observed value of 0.4e 2 /ǫl c .…”

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confidence: 91%

Tunneling into a two-dimensional electron system in a strong magnetic field

1993

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We investigate the properties of the one-electron Green's function in an interacting two-dimensional electron system in a strong magnetic field, which describes an electron tunneling into such a system. From finite-size diagonalization, we find that its spectral weight is suppressed near zero energy, reaches a maximum at an energy of about 0.2e 2 /ǫl c , and decays exponentially at higher energies. We propose a theoretical model to account for the low-energy behavior. For the case of Coulomb interactions between the electrons, at even-denominator filling factors such as ν = 1/2, we predict that the spectral weight varies as e −ω 0 /|ω| , for ω → 0.

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confidence: 91%

Tunneling into a two-dimensional electron system in a strong magnetic field

1993

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“…If one assumes particle-hole symmetry in the partially full LL, then the symmetric point will occur when the total filling factor is N + 1/2. The relation (3) seems to be in reasonable agreement with the experiment [9]. In fact, the conductivity tensor (2) satisfies the more general semicircle relation (1), which is valid also away from the symmetric point.…”

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confidence: 77%

Conductivity Tensor of Striped Quantum Hall Phases

2000

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We study the transport properties of pinned striped quantum Hall phases. We show that under quite general assumptions, the macroscopic conductivity tensor satisfies a semicircle law. In particular, this result is valid for both smectic and nematic stripe phases, independent of the presence of topological and orientational defects such as dislocations and grain boundaries. As a special case, our results explain the experimental validity of a product rule for the dissipative part of the resistivity tensor, which was previously derived by MacDonald and Fisher for a perfect stripe structure.PACS numbers: 73.40. Hm, 73.20.Dx, Recent experiments [1,2] have revealed strikingly anisotropic dc transport properties of very clean two dimensional (2D) electron systems when the Landau level filling factor is close to ν = N + 1/2, and N ≥ 4 is an integer. It is believed that this is related to previous theoretical proposals [3,4] that Coulomb interactions would lead to an instability towards charge-density wave (CDW) formation in high, spin resolved, Landau levels (LL). Specifically, formation of a striped phase of the uppermost Landau level was predicted when it is close to half filling, while a "bubble phase" should be favorable further away from half filling. The striped phase consists of one-dimensional stripes alternating between the integer filling factors N and N + 1 with period of order of the cyclotron radius R c . In the bubble phase, clusters of minority filling factor with size R c order in a triangular lattice. These predictions, obtained within the HartreeFock (HF) approximation, have also been supported by numerical exact diagonalization studies [5].At finite temperature and/or in the presence of disorder, the perfect stripe ordering predicted by HF calculations will presumably be destroyed. The unidirectional CDW shares the symmetries of 2D smectic liquid crystals [6]. This implies that if there is no external force tending to align the stripes, then a dislocation will cost only a finite amount of energy and thus there will be a finite density of dislocations at non-zero temperatures. This is expected to destroy translational long-range order, except at zero temperature, but preserve quasi-longrange orientational order of the remaining stripe segments, characteristic of a 2D nematic phase. The orientational order would be effectively locked in by any small added anisotropy. As the temperature becomes large enough, there will be a Kosterlitz-Thouless transition to an isotropic state in which the stripe segments lose their orientational order. Short-range stripe order should disappear completely only around the presumably much higher HF transition temperature.Transport properties of the striped phases should be affected by even small amounts of disorder on the substrate, which will pin the stripe positions at low temperatures. Disorder should also lead to a finite density of dislocations, even at zero temperature. Moreover, since the forces aligning the stripes are believed to be very weak, steps or other large-...

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“…In this context we mention that the SDW softening indicating a phase transition to the canted phase is a long wavelength instability, and therefore optical spectroscopy 41 may also be useful in studying our proposed ν = 2 double-layer phase diagram. Both of these pro- 38,39 has been that the naive ν = 2 level crossing phenomenon (at ∆ z = ∆ sas ) between ferromagnetic and symmetric phases, which would exist in the absence of our intervening canted phase, if it happens at all in double-layer systems, must happen at magnetic fields much lower than that satisfying ∆ z = ∆ sas condition. This is, of course, exactly what our phase diagram (see Fig.…”

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confidence: 95%

Canted antiferromagnetic and spin-singlet quantum Hall states in double-layer systems

1998

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We present details of earlier studies (Zheng et al, Phys. Rev. Lett. 78, 310 (1997) and Das Sarma et al, ibid 79, 917 (1997)) and additional new results on double-layer quantum Hall systems at a total filling ν = 2ν 1 , where a single layer at filling ν 1 forms a ferromagnetic, fully spin-polarized, gapped incompressible quantum Hall state. For the case ν 1 = 1, a detailed Hartree-Fock analysis is carried out on a realistic, microscopic Hamiltonian. Apart from the state continuously connected to the ground state of two well separated layers, we find two double-layer quantum Hall phases: one with a finite interlayer antiferromagnetic spin ordering in the plane orthogonal to the applied field (the 'canted' state), and the other a spin singlet. The quantum transitions between the various quantum Hall states are continuous, and are signaled by the softening of collective intersubband spin density excitations. For the case of general ν 1 , closely related results are obtained by a semi-phenomenological continuum quantum field theory description of the low-lying spin excitations using a non-linear sigma model. Because of its broken symmetry, the canted phase supports a linearly dispersing Goldstone mode and has a finite temperature Kosterlitz-Thouless transition. We present results on the form of the phase diagram, the magnitude of the canted order parameter, the collective

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Cited by 10 publications

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Tunneling into a two-dimensional electron system in a strong magnetic field

Tunneling into a two-dimensional electron system in a strong magnetic field

Conductivity Tensor of Striped Quantum Hall Phases

Canted antiferromagnetic and spin-singlet quantum Hall states in double-layer systems

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