Areas of superconductivity and giant proximity effects in underdoped cuprates

We investigate the low-energy quasiparticle excitation spectra of cuprate superconductors by incorporating both superconductivity (SC) and competing orders (CO) in the bare Green's function and quantum phase fluctuations in the proper self-energy. Our approach provides consistent explanations for various empirical observations, including the excess subgap quasiparticle density of states, "dichotomy" in the momentum-dependent quasiparticle coherence and the temperature-dependent gap evolution, and the presence (absence) of the low-energy pseudogap in hole-(electron-) type cuprates depending on the relative scale of the CO and SC energy gaps. 74.25.Jb, 74.50.+r Keywords: Quasiparticle spectra; pseudogap; competing orders; cuprate superconductors Cuprate superconductors differ fundamentally from conventional superconductors in that they are doped Mott insulators with strong electronic correlation that leads to possibilities of different competing orders (CO) in the ground state besides superconductivity (SC) [1][2][3][4][5][6][7][8]. The existence of competing orders and the proximity to quantum criticality [2,3,7,8] gives rise to unconventional low-energy excitations of the cuprates, manifested as weakened superconducting phase stiffness [6], occurrence of excess subgap quasiparticle density of states (DOS) [9], spatial modulations in the lowtemperature quasiparticle spectra that are unaccounted for by Bogoliubov quasiparticles alone [10][11][12], "dichotomy" in the momentum-dependent quasiparticle coherence [13] and temperature-dependent gap evolution [14], and the presence (absence) of the low-energy pseudogap (PG) [9,15,16] and Nernst effect [17] in the hole (electron)-type cuprates above the SC transition. Microscopically, the existence of CO is likely responsible for various non-universal phenomena among different cuprates [8,9,18,19]. Macroscopically, the weakened superconducting phase stiffness and proximity to CO can give rise to strong fluctuations that lead to the extreme type-II nature and rich vortex dynamics [8,20,21].To date there are two typical theoretical approaches to describing the quasiparticle excitation spectra of the cuprates. One approach takes the BCS-like Hamiltonian as the unperturbed mean-field state and a competing order, pinned by disorder, as the perturbation that gives rise to a weak scattering potential for the Bogoliubov quasiparticles [11,[22][23][24]. The other approach begins with the BCS-like Hamiltonian and includes superconducting phase fluctuations in the proper self-energy correction [25,26]. However, no quantitative calculations have been made by incorporating both CO and quantum phase fluctuations in the SC state. The objective of this work is to consider the latter scenario and compute the corresponding low-energy excitation spectra with realistic physical parameters for comparison with experiments. We find that the low-energy excitations thus derived differ from typical Bogoliubov quasiparticles and can account for various puzzling phenomena aforementioned....

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“…This notion of coexisting "puddles" of SC and AFM (with AFM being the relevant CO) has been investigated numerically in Ref. [42].…”

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confidence: 99%

Effects of competing orders and quantum phase fluctuations on the low-energy excitations and pseudogap phenomena of cuprate superconductors

Chen¹,

Beyer²,

Yeh³

2007

Solid State Communications

120

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“…A similar method was recently used 12 to study the phase diagram of a phenomenological model for high-T c superconductors. The authors 12 found that phase fluctuations can account for several features of the high-T c superconductors, among them the existence of a disorder-driven pseudo-gap state 11 . To demonstrate the possible relevance of our work, in the inset of Fig.…”

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confidence: 99%

Nature of the superconductor–insulator transition in disordered superconductors

Dubi

Meir

Avishai

2007

Nature

349

360

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The interplay of superconductivity and disorder has intrigued scientists for several decades. Disorder is expected to enhance the electrical resistance of a system, whereas superconductivity is associated with a zero-resistance state. Although, superconductivity Superconductivity-the occurrence of the zero-resistance state-has been a central issue in solid-state physics for nearly a hundred years. About half a century after its discovery Bardeen, Cooper and Schreiffer 13 (BCS) explained its microscopic foundation. BCS theory

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“…8,9,[14][15][16][17][18][19][20][21][22][23] Supposed that a few nanoscale SC domains are developed in the CuO 2 plane, magnetic fluxes are expelled from the nanoscale SC domains due to the Meissner effect. In this case, the internal magnetic field parallel to the initial muon polarization inside the SC domains decrease and the bending of the magnetic fluxes generates the internal magnetic field perpendicular to the initial J. Phys.…”

Section: Possible Emergence Of Superconducting Domains Above T Cmentioning

confidence: 99%

“…[7][8][9][10][11][12][13] Theoretical works have suggested that the superconductivity develops in a form of small domains at temperatures far above T c and that the increase in the number of the small SC domains brings about the bulk SC state owing to percolation or Josephson coupling. [14][15][16] The recent study of the scanning tunneling microscopy (STM) in BSCCO has suggested that pairing gaps tend to nucleate in nanoscale regions at temperatures far above T c . [17][18][19] Moreover, both the linear diamagnetic response in the magnetization measurements in Tl 2 Ba 2 CuO 6+δ , 20,21 the hysteresis in the low-field magnetization curve in LSCO, 22 the enhancement of the relaxation rate in the transverse-field (TF) muon-spin-relaxation (µSR) measurements in LSCO and YBCO 23 and the result of high-frequency conductivity measurements in LSCO [8][9][10] have also suggested the presence of small SC domains at temperatures above T c .…”

Section: Introductionmentioning

confidence: 99%

Development of Spatial Inhomogeneity of Internal Magnetic Field Above T_c in Bi₂Sr₂Ca₁₋_xY_xCu₂O_8+δ Observed by Longitudinal-Field Muon Spin Relaxation

et al. 2014

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Longitudinal-field muon-spin-relaxation measurements have revealed inhomogeneous distribution of the internal magnetic field at temperatures above the bulk superconducting (SC) transition temperature, T c , in slightly overdoped Bi 2 Sr 2 Ca 1−x Y x Cu 2 O 8+δ . The distribution width of the internal magnetic field, ∆, evolves continuously with decreasing temperature toward T c . The origin of the increase in ∆ is discussed in terms of the creation of SC domains in a sample.

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Areas of superconductivity and giant proximity effects in underdoped cuprates

Cited by 102 publications

References 35 publications

Effects of competing orders and quantum phase fluctuations on the low-energy excitations and pseudogap phenomena of cuprate superconductors

Effects of competing orders and quantum phase fluctuations on the low-energy excitations and pseudogap phenomena of cuprate superconductors

Nature of the superconductor–insulator transition in disordered superconductors

Development of Spatial Inhomogeneity of Internal Magnetic Field Above T_c in Bi₂Sr₂Ca₁₋_xY_xCu₂O_8+δ Observed by Longitudinal-Field Muon Spin Relaxation

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Areas of superconductivity and giant proximity effects in underdoped cuprates

Cited by 102 publications

References 35 publications

Effects of competing orders and quantum phase fluctuations on the low-energy excitations and pseudogap phenomena of cuprate superconductors

Effects of competing orders and quantum phase fluctuations on the low-energy excitations and pseudogap phenomena of cuprate superconductors

Nature of the superconductor–insulator transition in disordered superconductors

Development of Spatial Inhomogeneity of Internal Magnetic Field Above Tc in Bi2Sr2Ca1−xYxCu2O8+δ Observed by Longitudinal-Field Muon Spin Relaxation

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Development of Spatial Inhomogeneity of Internal Magnetic Field Above T_c in Bi₂Sr₂Ca₁₋_xY_xCu₂O_8+δ Observed by Longitudinal-Field Muon Spin Relaxation