Concepts in High Temperature Superconductivity

Carlson, E. W.; Emery, V. J.; Kivelson, Steven; Orgad, Dror

doi:10.1007/978-3-540-73253-2_21

Cited by 97 publications

(148 citation statements)

References 539 publications

(405 reference statements)

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“…Since the sign of the J-term in (3) is irrelevant (the sign of the K-term is relevant) the superfluid-striped transition could possibly, in an extended parameter space, connect to the order-disorder transition in the two-dimensional Heisenberg antiferromagnet with frustrating interactions [31]. We also note that the staggered-striped-superfluid phase behavior versus J/K shows interesting similarities to the high-T c cuprates, where the pseudogap phase intervening between the antiferromagnetic and superconducting phases exhibits strong stripe correlations [30]. Although the microscopic physics and symmetries are clearly different, a detailed study of the staggered-striped transition may still be useful in this context.…”

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confidence: 66%

Striped Phase in a QuantumXYModel with Ring Exchange

et al. 2002

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We present quantum Monte Carlo results for a square-lattice S = 1/2 XY-model with a standard nearest-neighbor coupling J and a four-spin ring exchange term K. Increasing K/J, we find that the ground state spin-stiffness vanishes at a critical point at which a spin gap opens and a striped bondplaquette order emerges. At still higher K/J, this phase becomes unstable and the system develops a staggered magnetization. We discuss the quantum phase transitions between these phases.PACS numbers: 75.10.Jm, 75.40.Mg, Ring exchange interactions have for a long time been known to be present in a variety of quantum many-body systems [1] and have been investigated rather thoroughly in solid 3 He [2]. They are also important for electrons in the Wigner crystal phase [3,4]. In strongly correlated electron systems, such as the high-T c cuprates and related antiferromagnets, ring exchange processes are typically much weaker than the pair exchange J [5] and are often neglected. Four-spin ring exchange has, however, been argued to be responsible for distinct features in the magnetic Raman [6] and optical absorption spectra [7]. Neutron measurements of the magnon dispersion have also become sufficiently accurate to detect deviations from the standard pair exchange Hamiltonian (the Heisenberg model) and such discrepancies have been attributed to ring exchange [8,9]. Recently, ring exchange has attracted interest as a potentially important interaction that could lead to novel quantum states of matter, in particular 2D electronic spin liquids with fractionalized excitations [10,11,12,13,14,15]. Furthermore, for bosons on a square lattice ring exchange has been shown to give rise to a "exciton Bose liquid" phase [16].Here we study the effects of ring exchange in one of the most basic quantum many-body Hamiltonians-the spin-1/2 XY-model on a 2D square lattice. We use a quantum Monte Carlo method (stochastic series expansion, hereafter SSE [17,18,19]) to study the low-temperature behavior of this system including a four-spin ring term. Defining bond and plaquette exchange operatorsthe Hamiltonian iswhere ij denotes a pair of nearest-neighbor sites and ijkl are sites on the corners of a plaquette. For K = 0 this is the standard quantum XY-model, or, equivalently, hard-core bosons at half-filling with no interactions apart from the single-occupancy constraint. This system undergoes a Kosterlitz-Thouless transition at T /J ≈ 0.68 [20,21] and has a T = 0 ferromagnetic moment M x = S x i ≈ 0.44 [22,23]. The K-term corresponds to retaining only the purely x-and y-terms of the full cyclic exchange.In a soft-core version of the pure ring model (J = 0), Paramekanti et al. recently found a compressible but non-superfluid phase (exciton Bose liquid) for weak onsite repulsion U [16]. As the hard-core limit is approached they found a transition to a staggered chargedensity-wave phase. Hence, the ground state of the spin Hamiltonian (3) can be expected to change from an easyplane ferromagnet with a finite spin stiffness ρ s and a magnetization M x at...

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confidence: 66%

Striped Phase in a QuantumXYModel with Ring Exchange

et al. 2002

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“…The development of 2D superconductivity would be limited by the Josephson coupling between neighboring stripes. Further elaboration on this topic is provided by Carlson et al [168] and by Kivelson and Fradkin [169].…”

Section: General Relevance Of Stripes To Cupratesmentioning

confidence: 99%

Spins, stripes, and superconductivity in hole-doped cuprates

Tranquada¹

2013

AIP Conference Proceedings

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Abstract. One of the major themes in correlated electron physics over the last quarter century has been the problem of high-temperature superconductivity in hole-doped copper-oxide compounds. Fundamental to this problem is the competition between antiferromagnetic spin correlations, a symptom of strong Coulomb interactions, and the kinetic energy of the doped carriers, which favors delocalization. After discussing some of the early challenges in the field, I describe the experimental picture provided by a variety of spectroscopic and transport techniques. Then I turn to the technique of neutron scattering, and discuss how it is used to determine spin correlations, especially in model systems of quantum magnetism. Neutron scattering and complementary techniques have determined the extent to which antiferromagnetic spin correlations survive in the cuprate superconductors. One experimental case involves the ordering of spin and charge stripes. I first consider related measurements on model compounds, such as La 2−x Sr x NiO 4+δ , and then discuss the case of La 2−x Ba x CuO 4 . In the latter system, recent transport studies have demonstrated that quasi-two-dimensional superconductivity coexists with the stripe order, but with frustrated phase order between the layers. This has led to new concepts for the coexistence of spin order and superconductivity. While the relevance of stripe correlations to high-temperature superconductivity remains a subject of controversy, there is no question that stripes are an intriguing example of electron matter that results from strong correlations.Keywords: superconductivity, antiferromagnetism, charge order, stripes, cuprates, nickelates, neutron scattering PACS: 78.70.Nx OPENING REMARKSCuprate superconductivity is a fascinating field, with an enormous literature. There have been a great many measurements done on a wide variety of cuprate families. There are numerous theoretical perspectives on the nature of these materials and on the mechanism of superconductivity.I approach this topic not as an unbiased outside observer, but as a participant who has been around from the beginning. My purpose here is not to present a balanced review of all work and perspectives in the field, as there would be too much to cover. Instead, I will present one story about hole-doped cuprates, based largely on experiment and especially on neutron scattering studies. Since one of the main advantages of neutrons is their ability to follow dynamic antiferromagnetic spin correlations, it should come as no surprise that they will play a key role in the story.I have tried to cite sufficient references (especially review articles) so that the curious reader can find further information and potentially a starting point in searching the broader literature. I have not attempted to cite all relevant work, as that would have been

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“…Among them one should differentiate between checkerboard superstructures [127][128][129][130][131][132] (these are quite natural for the electron distribution with four-fold rotational symmetry inherent to cuprates with their quasi-two-dimensional CuO 2 planes [93,[133][134][135][136]) and distorted states with broken rotational symmetry, e.g., unidirectional CDWs [129,130,[137][138][139][140] or more disordered nematic configurations [56,124,[141][142][143][144]. If thin static or fluctuating charged domains alternate with spin-ordered ones, i.e., a peculiar unidirectional phase separation occurs (more general phase separation scenarios were proposed long ago for versatile objects [145][146][147]), the electronic state of a crystal is frequently called a stripe phase [56,137,[148][149][150]. One should also bear in mind the possibility of loop-current electron ordering [56,124,151], going back to states predicted for the excitonic insulator [152].…”

Section: Cdw and Pseudogap Evidence In Cupratesmentioning

confidence: 99%

d-Wave Superconductivity and s-Wave Charge Density Waves: Coexistence between Order Parameters of Different Origin and Symmetry

Ekino

Gabovich

et al. 2011

Symmetry

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A review of the theory describing the coexistence between d-wave superconductivity and s-wave charge-density-waves (CDWs) is presented. The CDW gapping is identified with pseudogapping observed in high-T c oxides. According to the cuprate specificity, the analysis is carried out for the two-dimensional geometry of the Fermi surface (FS). Phase diagrams on the σ 0 − α plane-here, σ 0 is the ratio between the energy gaps in the parent pure CDW and superconducting states, and the quantity 2α is connected with the degree of dielectric (CDW) FS gapping-were obtained for various possible configurations of the order parameters in the momentum space. Relevant tunnel and photoemission experimental data for high-T c oxides are compared with theoretical predictions. A brief review of the results obtained earlier for the coexistence between s-wave superconductivity and CDWs is also given.

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Concepts in High Temperature Superconductivity

Cited by 97 publications

References 539 publications

Striped Phase in a QuantumXYModel with Ring Exchange

Striped Phase in a QuantumXYModel with Ring Exchange

Spins, stripes, and superconductivity in hole-doped cuprates

d-Wave Superconductivity and s-Wave Charge Density Waves: Coexistence between Order Parameters of Different Origin and Symmetry

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