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

Sarma, S. Das; Sachdev, Subir; Zheng, Luyao

doi:10.1103/physrevb.58.4672

Cited by 98 publications

(113 citation statements)

References 49 publications

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“…(ii ) Double layer quantum Hall systems at filling factor ν = 2 exhibit ground states with different types of magnetic order [3]. Recent light scattering experiments [4] have probed the fluctuation of the magnetic order parameter in the vicinity of the quantum transitions between the states.…”

Section: Introductionmentioning

confidence: 99%

Universal relaxational dynamics near two-dimensional quantum critical points

Sachdev¹

1999

Phys. Rev. B

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104

152

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We describe the nonzero temperature (T ), low frequency (ω) dynamics of the order parameter near quantum critical points in two spatial dimensions (d), with a special focus on the regimehω ≪ k B T . For the case of a 'relativistic', O(n)-symmetric, bosonic quantum field theory we show that, for small ǫ = 3 − d, the dynamics is described by an effective classical model of waves with a quartic interaction. We provide analytical and numerical analyses of the classical wave model directly in d = 2. We describe the crossover from the finite frequency, "amplitude fluctuation", gapped quasiparticle mode in the quantum paramagnet (or Mott insulator), to the zero frequency "phase" (n ≥ 2) or "domain wall" (n = 1) relaxation mode near the ordered state. For static properties, we show how a surprising, duality-like transformation allows an exact treatment of the strong-coupling limit for all n. For n = 2, we compute the universal T dependence of the superfluid density below the Kosterlitz-Thouless temperature, and discuss implications for the high temperature superconductors. For n = 3, our computations of the dynamic structure factor relate to neutron scattering experiments on La 1.85 Sr 0.15 CuO 4 , and to light scattering experiments on double layer quantum Hall systems. We expect that closely related effective classical wave models will apply also to other quantum critical points in d = 2. Although computations in appendices do rely upon technical results on the ǫ-expansion of quantum critical points obtained in earlier papers, the physical discussion in the body of the paper is self-contained, and can be read without consulting these earlier works.

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Section: Introductionmentioning

confidence: 99%

Universal relaxational dynamics near two-dimensional quantum critical points

Sachdev¹

1999

Phys. Rev. B

Self Cite

104

152

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“…The analyticity at s = 0 is required by the absence of any thermodynamic singularity at finite T for ∆ = 0. This is a key property, which was in fact used to obtain the answer in (33). The exact expression for the function G I (s) is also known…”

Section: Finite Temperature Crossoversmentioning

confidence: 99%

“…For technical reasons not explored here, the rotor models also describe integer spin chains, and a large class of Heisenberg antiferromagnets in higher dimensions. Finally, rotor models are also useful in double-layer quantum Hall systems [33], where superexchange effects lead to an antiferromagnetic coupling between the electrons in the two layers [34]. These systems (excluding the doublelayer quantum Hall system for which the reader is referred to the literature) will be described in more detail in the following subsections.…”

Section: O(3) Quantum Rotors Between One and Three Dimensionsmentioning

confidence: 99%

Dynamics and Transport Near Quantum-Critical Points

Sachdev

1998

Dynamical Properties of Unconventional Magnetic Systems

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Abstract. The physics of non-zero temperature dynamics and transport near quantum-critical points is discussed by a detailed study of the O(N )-symmetric, relativistic, quantum field theory of a N -component scalar field in d spatial dimensions. A great deal of insight is gained from a simple, exact solution of the long-time dynamics for the N = 1 d = 1 case: this model describes the critical point of the Ising chain in a transverse field, and the dynamics in all the distinct, limiting, physical regions of its finite temperature phase diagram is obtained. The N = 3, d = 1 model describes insulating, gapped, spin chain compounds: the exact, low temperature value of the spin diffusivity is computed, and compared with NMR experiments. The N = 3, d = 2, 3 models describe Heisenberg antiferromagnets with collinear Néel correlations, and experimental realizations of quantum-critical behavior in these systems are discussed. Finally, the N = 2, d = 2 model describes the superfluid-insulator transition in lattice boson systems: the frequency and temperature dependence of the the conductivity at the quantum-critical coupling is described and implications for experiments in two-dimensional thin films and inversion layers are noted.

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“…They have been observed experimentally [9,10,11]. The last one is a canted antiferromagnetic phase (C-phase), which is predicted [12,13,14,15,16,17] between the spin and ppin phase in a phase diagram. The C-phase is an exotic phase, where spins on the front layer and the back layer exhibit ferromagnetic properties in the perpendicular direction and simultaneously antiferromagnetic properties to the two dimensional layer directions.…”

Section: Introductionmentioning

confidence: 99%

SU(4) coherent effects to the canted antiferromagnetic phase in bilayer quantum Hall systems at ν=2

Hasebe¹

2003

Physics Letters A

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In bilayer quantum Hall (BLQH) systems at ν=2, three different kinds of ground states are expected to be realized, i.e. a spin polarized phase (spin phase), a pseudospin polarized phase (ppin phase) and a canted antiferromagnetic phase (C-phase). An SU(4) scheme gives a powerful tool to investigate BLQH systems which have not only the spin SU(2) but also the layer (pseudospin) SU(2) degrees of freedom. In this paper, we discuss an origin of the C-phase in the SU(4) context and investigate SU(4) coherent effects to it. We show peculiar operators in the SU(4) group which do not exist in SUspin(2)⊗SUppin(2) group play a key role to its realization. It is also pointed out that not only spins but also pseudospins are "canted" in the C-phase.

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

Cited by 98 publications

References 49 publications

Universal relaxational dynamics near two-dimensional quantum critical points

Universal relaxational dynamics near two-dimensional quantum critical points

Dynamics and Transport Near Quantum-Critical Points

SU(4) coherent effects to the canted antiferromagnetic phase in bilayer quantum Hall systems at ν=2

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