Possible nematic to smectic phase transition in a two-dimensional electron gas at half-filling

Qian, Qi; Nakamura, James; Fallahi, Saeed; Gardner, G. C.; Manfra, Michael J.

doi:10.1038/s41467-017-01810-y

Cited by 33 publications

(31 citation statements)

References 45 publications

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“…23 predicts considerably stronger T -dependence of R xx and R yy at ν = i/2 [24] than away from half filling and our data do not reflect that. Therefore, the observed dependencies on ν and T are inconsistent with QHS or a nematic-to-smectic transition [25]. Instead, the observed low-temperature emergence of unexpected extrema in R xx and R yy along with the plateau-like features in R H likely reflects the formation of another competing ground state.…”

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confidence: 82%

Anomalous Nematic States in High Half-Filled Landau Levels

Shi

Zudov

et al. 2020

Phys. Rev. Lett.

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It is well established that the ground states of a two-dimensional electron gas with half-filled high (N ≥ 2) Landau levels are compressible charge-ordered states, known as quantum Hall stripe (QHS) phases. The generic features of QHSs are a maximum (minimum) in a longitudinal resistance Rxx (Ryy) and a non-quantized Hall resistance RH . Here, we report on emergent minima (maxima) in Rxx (Ryy) and plateau-like features in RH in half-filled N ≥ 3 Landau levels. Remarkably, these unexpected features develop at temperatures considerably lower than the onset temperature of QHSs, suggesting a new ground state.

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confidence: 82%

Anomalous Nematic States in High Half-Filled Landau Levels

Shi

Zudov

et al. 2020

Phys. Rev. Lett.

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“…Indeed, a strong resistance anisotropy at the Landau level filling factors ν = 9/2, 11/2, 13/2, ... signals a ground state state with broken rotational symmetry [2,3]. There are two distinct ground states consistent with such an anisotropy: the smectic and nematic phases [4][5][6][7]15]. The difference between these two is that the former has unidirectional translational order, whereas the latter does not.…”

Section: Introductionmentioning

confidence: 99%

Electron–electron interactions and the paired-to-nematic quantum phase transition in the second Landau level

et al. 2018

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In spite of its ubiquity in strongly correlated systems, the competition of paired and nematic ground states remains poorly understood. Recently such a competition was reported in the two-dimensional electron gas at filling factor ν = 5/2. At this filling factor a pressure-induced quantum phase transition was observed from the paired fractional quantum Hall state to the quantum Hall nematic. Here we show that the pressure-induced paired-to-nematic transition also develops at ν = 7/2, demonstrating therefore this transition in both spin branches of the second orbital Landau level. However, we find that pressure is not the only parameter controlling this transition. Indeed, ground states consistent with those observed under pressure also develop in a sample measured at ambient pressure, but in which the electron–electron interaction was tuned close to its value at the quantum critical point. Our experiments suggest that electron–electron interactions play a critical role in driving the paired-to-nematic transition.

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“…In Landau levels N ≥ 1 and higher, other scales may come into play. This fact is evinced by the recent experiments near ν = 5/2 which find an interplay between a (presumably uniform) paired state and a compressible nematic phase [28], and between a compressible nematic phase and a stripe phase (albeit in the N = 2 Landau level) [16].…”

Section: A Spectra Of Px + Ipy Pdw Fqh Statesmentioning

confidence: 96%

Pair-Density-Wave Order and Paired Fractional Quantum Hall Fluids

2019

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The properties of the isotropic incompressible ν = 5/2 fractional quantum Hall (FQH) state are described by a paired state of composite fermions in zero (effective) magnetic field, with a uniform px +ipy pairing order parameter, which is a non-Abelian topological phase with chiral Majorana and charge modes at the boundary. Recent experiments suggest the existence of a proximate nematic phase at ν = 5/2. This finding motivates us to consider an inhomogeneous paired state -a px + ipy pair-density-wave (PDW) -whose melting could be the origin of the observed liquidcrystalline phases. This state can viewed as an array of domain and anti-domain walls of the px + ipy order parameter. We show that the nodes of the PDW order parameter, the location of the domain walls (and anti-domain walls) where the order parameter changes sign, support a pair of symmetry-protected counter-propagating Majorana modes. The coupling behavior of the domain wall Majorana modes crucially depends on the interplay of the Fermi energy EF and the PDW pairing energy E pdw . The analysis of this interplay yields a rich set of topological states: (1) In the weak coupling regime (EF > E pdw ), the hybridization of domain walls leads to a Majorana Fermi surface (MFS), which is protected by inversion and particle-hole symmetries.(2) As the MFS shrinks towards degenerate Dirac points, lattice effects render it unstable towards an Abelian striped phase with two co-propagating Majorana modes at the boundary. (3) An uniform component of the order parameter, which breaks inversion symmetry, gaps the MFS and causes the system to enter a non-Abelian FQH state supporting a chiral Majorana edge state. (4) In the strong coupling regime, EF < E pdw , the bulk fermionic spectrum becomes gapped; this is a trivial phase with no chiral Majorana edge states, which is in the universality class of an Abelian Halperin paired state. The pair-density-wave order state in paired FQH system provides a fertile setting to study Abelian and non-Abelian FQH phases -as well as transitions thereof -tuned by the strength of the paired liquid crystalline order.CONTENTS * These authors contributed equally to the work.

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Possible nematic to smectic phase transition in a two-dimensional electron gas at half-filling

Cited by 33 publications

References 45 publications

Anomalous Nematic States in High Half-Filled Landau Levels

Anomalous Nematic States in High Half-Filled Landau Levels

Electron–electron interactions and the paired-to-nematic quantum phase transition in the second Landau level

Pair-Density-Wave Order and Paired Fractional Quantum Hall Fluids

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