Tilt-Induced Localization and Delocalization in the Second Landau Level

Csáthy, Gábor; Xia, J. S.; Vicente, C. L.; Adams, E. D.; Sullivan, N. S.; Störmer, H. L.; Tsui, D. C.; Pfeiffer, L. N.; West, K. W.

doi:10.1103/physrevlett.94.146801

Cited by 45 publications

(33 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We note that in previous tilt-field experiments, inplane magnetic fields consistently enhance the IP, which are revealed as resistance spikes around 5/2 [22][23][24]. Here this effect appears to be weak in the tilt angle range θ ∼ 30 • .…”

mentioning

confidence: 85%

“…However, to date all the experimental results have contradicted this simple prediction: the 5/2 FQHE is found to be weakened in a tilted field [13][14][15][16]. Competition with a striped many-electron phase could be a plausible cause for the complex response of the 5/2 state in a tilted field [22][23][24]. On the other hand, Wójs et al point to an interesting possibility based on numerical calculations in wide GaAs/AlGaAs quantum wells (QWs), the MR state could be depolarized by forming a Skyrmionspin texture or spin topological defects [25,26].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Enhancement of theν=5/2Fractional Quantum Hall State in a Small In-Plane Magnetic Field

et al. 2012

Self Cite

View full text Add to dashboard Cite

Using a 50-nm width, ultra-clean GaAs/AlGaAs quantum well, we have studied the Landau level filling factor ν = 5/2 fractional quantum Hall effect in a perpendicular magnetic field B ∼ 1.7 T and determined its dependence on tilted magnetic fields. Contrary to all previous results, the 5/2 resistance minimum and the Hall plateau are found to strengthen continuously under an increasing tilt angle 0 < θ < 25 • (corresponding to an in-plane magnetic field 0 < B < 0.8 T). In the same range of θ the activation gaps of both the 7/3 and the 8/3 states are found to increase with tilt. The 5/2 state transforms into a compressible Fermi liquid upon tilt angle θ > 60 • , and the composite fermion series [2+p/(2p ± 1)], p = 1, 2 can be identified. Based on our results, we discuss the relevance of a Skyrmion spin texture at ν = 5/2 associated with small Zeeman energy in wide quantum wells, as proposed by Wójs et al., Phys. Rev. Lett. 104, 086801 (2010 The fractional quantum Hall effect (FQHE) observed at Landau level (LL) filling factor ν = 5/2 [1-3] has received much attention since theory suggests that its quasiparticles may obey non-Abelian statistics [4,5]. Here ν = n e h/eB, where n e is the sheet density of 2D electrons, and B is the magnetic field. To date, most of the evidence supporting the non-Abelian nature of 5/2 is from exact diagonalization or numerical calculations [6,7] based on modeling electron-electron interaction potentials (including the Coulomb potential), although more recently experimental evidence has accumulated supporting quarter-charged quasiparticles at 5/2 [8-10], or nonAbelian statistics [10]. If the predicted non-Abelian properties can be firmly established both theoretically and experimentally, the braiding of these non-Abelian particles can form the basis for topologically protected quantum computation [11].The proposed Moore-Read (MR) Pfaffian wavefunction for 5/2 requires the spin being at least partially polarized. Recent numerical results indicate that the 5/2 state in a GaAs quantum well system is spin-polarized even in the limit of vanishing Zeeman energy [12]. Experimental investigations on spin polarization at 5/2 from electrical transport [13][14][15][16] and optical measurements [17][18][19] have been reported, but these results provide only indirect determination of the spin states. Recent resistively detected nuclear magnetic resonance measurements point to a fully spin-polarized ground state (GS) at 5/2 at a magnetic field around 5 T [20,21].It is anticipated that increasing the Zeeman energy would help to stabilize the spin-polarized GS in the presence of fluctuations. Therefore, a tilted magnetic field is supposed to enhance the FQHE at 5/2 [12]. However, to date all the experimental results have contradicted this simple prediction: the 5/2 FQHE is found to be weakened in a tilted field [13][14][15][16]. Competition with a striped many-electron phase could be a plausible cause for the complex response of the 5/2 state in a tilted field [22][23][24]. On the other hand, Wójs et al...

show abstract

mentioning

confidence: 85%

mentioning

confidence: 99%

Enhancement of theν=5/2Fractional Quantum Hall State in a Small In-Plane Magnetic Field

et al. 2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…The total magnetic field in that case points along an angle θ with respect to the vertical axis, which we refer to as the tilt angle. This technique has been immensely popular in experiment [22][23][24][25][26][27][28][29][30][31] , e.g. as a probe for spin polarization: to the lowest order, the only effect of parallel field is to increase the Zeeman coupling, therefore it distinguishes a polarized ground state from an unpolarized one.…”

Section: Introductionmentioning

confidence: 99%

Fractional quantum Hall effect in a tilted magnetic field

Papić

2013

Phys. Rev. B

View full text Add to dashboard Cite

We discuss the orbital effect of a tilted magnetic field on the quantum Hall effect in parabolic quantum wells. Many-body states realized at the fractional 1/3 and 1/2 filling of the second electronic subband are studied using finite-size exact diagonalization. In both cases, we obtain the phase diagram consisting of a fractional quantum Hall fluid phase that persists for moderate tilts, and eventually undergoes a direct transition to the stripe phase. It is shown that tilting of the field probes the geometrical degree of freedom of fractional quantum Hall fluids, and can be partly related to the effect of band-mass anisotropy.

show abstract

“…The sample is tilted at an angle θ = 20°. The resulting small in-plane component of the magnetic field allows for welldefined FQHE states at ν = 5/2 and ν = 7/3 and also anisotropic phases in the second LL [3,4,22,23]. The filling factor is identified by the strong spin wave in the polarized ν = 3 state as described in the supplementary online information [39].…”

mentioning

confidence: 99%

“…When B is such that electrons fill states in higher (N ≥ 2) LL's, electrons form quantum phases referred to as stripe and bubble phases, which lead to transport anisotropy and reentrant integer quantum Hall effect (RIQHE) states [1][2][3]. The unique electron-electron interactions in the N=1 LL result in the presence of RIQHE states and stripe phases in addition to even-and odd-denominator FQHE states [3,4]. FQHE states in the second (N=1) LL exhibit evendenominator states such as the one at ν = 5/2 [5,6], which is predicted to have non-Abelian excitations [7][8][9][10][11][12][13][14], has recently been studied by NMR [15,16], by light scattering methods [17,18], and in two-subband systems [19].…”

mentioning

confidence: 99%

Optical Emission Spectroscopy Study of Competing Phases of Electrons in the Second Landau Level

et al. 2016

View full text Add to dashboard Cite

Quantum phases of electrons in the filling factor range 2 ≤ ν ≤ 3 are probed by the weak optical emission from the partially populated second Landau level and spin wave measurements. Observations of optical emission include a multiplet of sharp peaks that exhibit a strong filling factor dependence. Spin wave measurements by resonant inelastic light scattering probe breaking of spin rotational invariance and are used to link this optical emission with collective phases of electrons. A remarkably rapid interplay between emission peak intensities manifests phase competition in the second Landau level.Ultra-clean two dimensional electron systems in the presence of high perpendicular magnetic fields B are a source of unexpected and fascinating quantum many-body physics that arises from the strong electron interactions combined with a reduction in dimensionality. When B is high enough for all electrons to occupy the lowest (N=0) Landau level (LL), the many-electron system forms liquids of the fractional quantum Hall effect (FQHE). When B is such that electrons fill states in higher (N ≥ 2) LL's, electrons form quantum phases referred to as stripe and bubble phases, which lead to transport anisotropy and reentrant integer quantum Hall effect (RIQHE) states [1][2][3]. The unique electron-electron interactions in the N=1 LL result in the presence of RIQHE states and stripe phases in addition to even-and odd-denominator FQHE states [3,4]. FQHE states in the second (N=1) LL exhibit evendenominator states such as the one at ν = 5/2 [5, 6], which is predicted to have non-Abelian excitations [7][8][9][10][11][12][13][14], has recently been studied by NMR [15,16], by light scattering methods [17,18], and in two-subband systems [19]. It has been predicted that the less studied FQHE state at ν = 2 + 1/3 = 7/3 could possess exotic quasiparticles in which composite fermions are dressed by a cloud of neutral excitations [20]. Since FQHE liquids as well as bubble and stripe phases can serve as ground states, the N=1 LL is home to a striking competition between quantum phases [21].The interplay of anisotropic phases with FQHE liquids in the second LL has been studied by introduction of in-plane magnetic fields [3,[22][23][24][25]. These experiments provide evidence that anisotropic smectic-or nematic-like phases with broken full rotational invariance coexist with quantum Hall liquids [26][27][28][29][30]. The large anisotropy induced in the system at the FQHE states at ν = 5/2 and ν = 7/3 by relatively small in-plane magnetic fields [22][23][24] supports interpretations in terms of a new state of electron matter with FQHE states that occur in the environment of a nematic stripe phase [30][31][32].We report optical emission experiments that probe quantum phases that emerge in the second LL of an ultra-clean 2D electron system. The optical recombination is from transitions across conduction to valence band states from electrons that partially populate the N=1 LL. This emission, while much weaker than the one originating in the N=0 LL (...

show abstract

Tilt-Induced Localization and Delocalization in the Second Landau Level

Cited by 45 publications

References 48 publications

Enhancement of theν=5/2Fractional Quantum Hall State in a Small In-Plane Magnetic Field

Enhancement of theν=5/2Fractional Quantum Hall State in a Small In-Plane Magnetic Field

Fractional quantum Hall effect in a tilted magnetic field

Optical Emission Spectroscopy Study of Competing Phases of Electrons in the Second Landau Level

Contact Info

Product

Resources

About