Book contents
- Frontmatter
- Contents
- Preface
- 1 A polaron theory of high-temperature superconductors
- 2 On the possibility of non-BCS superconductivity
- 3 A bipolaron Bose liquid in high-Tc superconductors
- 4 Spin polarons in high-Tc superconductors
- 5 The polaron scenario for high-Tc superconductors
- 6 Formation, phase separation and superconductivity of large bipolarons
- 7 Polarons and bipolarons in WO3−x and YBa2Cu3O7
- 8 Polaron bands in the far- and mid-infrared spectra of e-doped cuprates
- 9 Electron–phonon interaction of non-equilibrium carriers in the photoinduced state of YBa2Cu3O7−δ
- 10 Experimental evidence of local lattice distortion in superconducting oxides
- 11 The Hall effect due to small polarons and conduction in narrow energy bands
- 12 Static and dynamic conductivity of untwinned Y1Ba2Cu4O8: gaps or condensation?
- 13 The near infrared and optical absorption of high- Tc superconductors using powders
- 14 Polaronic theory of mid-infrared conductivity: a numerical cluster study
- 15 Electromagnetic properties of local pair superconductors
- 16 Electron–hole asymmetric polarons
- 17 On the nature of the superconducting state in high-Tc cuprates
- 18 High- Tc superconductivity with polarons and bipolarons: an approach from the insulating states
- 19 Coexistence of small-polaron and Anderson localization in high- Tc superconducting materials
- 20 Concentration and temperature-dependence of magnetic polaron spectra in the t–J model
- 21 Mass enhancement without band-narrowing in t–t′–J and related models: predictions for Fermi-surface and optical conductivity
- 22 Polarons in Peierls–Hubbard models
- 23 Exact estimates of inter-polaron coupling constants resulting in bipolaron formation
- 24 Coulomb interaction and the criteria for bipolaron formation
- 25 Large bipolarons and high-Tc materials
- 26 Collective excitations in the ground state of a two-dimensional attractive Fermi gas
- 27 Strong two-band electron self-trapping, state hybridization effects and related pressure-induced phenomena in semiconductors
- 28 Bismuth disproportionation in super- and semiconducting barium bismuthates
- 29 Magnetic polarons in concentrated and diluted magnetic semiconductors
- 30 Energy scales of exotic superconductors
- Index
5 - The polaron scenario for high-Tc superconductors
Published online by Cambridge University Press: 24 November 2009
- Frontmatter
- Contents
- Preface
- 1 A polaron theory of high-temperature superconductors
- 2 On the possibility of non-BCS superconductivity
- 3 A bipolaron Bose liquid in high-Tc superconductors
- 4 Spin polarons in high-Tc superconductors
- 5 The polaron scenario for high-Tc superconductors
- 6 Formation, phase separation and superconductivity of large bipolarons
- 7 Polarons and bipolarons in WO3−x and YBa2Cu3O7
- 8 Polaron bands in the far- and mid-infrared spectra of e-doped cuprates
- 9 Electron–phonon interaction of non-equilibrium carriers in the photoinduced state of YBa2Cu3O7−δ
- 10 Experimental evidence of local lattice distortion in superconducting oxides
- 11 The Hall effect due to small polarons and conduction in narrow energy bands
- 12 Static and dynamic conductivity of untwinned Y1Ba2Cu4O8: gaps or condensation?
- 13 The near infrared and optical absorption of high- Tc superconductors using powders
- 14 Polaronic theory of mid-infrared conductivity: a numerical cluster study
- 15 Electromagnetic properties of local pair superconductors
- 16 Electron–hole asymmetric polarons
- 17 On the nature of the superconducting state in high-Tc cuprates
- 18 High- Tc superconductivity with polarons and bipolarons: an approach from the insulating states
- 19 Coexistence of small-polaron and Anderson localization in high- Tc superconducting materials
- 20 Concentration and temperature-dependence of magnetic polaron spectra in the t–J model
- 21 Mass enhancement without band-narrowing in t–t′–J and related models: predictions for Fermi-surface and optical conductivity
- 22 Polarons in Peierls–Hubbard models
- 23 Exact estimates of inter-polaron coupling constants resulting in bipolaron formation
- 24 Coulomb interaction and the criteria for bipolaron formation
- 25 Large bipolarons and high-Tc materials
- 26 Collective excitations in the ground state of a two-dimensional attractive Fermi gas
- 27 Strong two-band electron self-trapping, state hybridization effects and related pressure-induced phenomena in semiconductors
- 28 Bismuth disproportionation in super- and semiconducting barium bismuthates
- 29 Magnetic polarons in concentrated and diluted magnetic semiconductors
- 30 Energy scales of exotic superconductors
- Index
Summary
Abstract
There is ample experimental evidence for localized polaronic charge carriers in high-Tc materials in the insulating phase as well as in the metallic phase at high temperatures. This would rule out a priori any condensation of bipolarons, since for that purpose they should be in free-particle-like states in the longwavelength limit. Yet, provided that the localized bipolarons hybridize with a band of itinerant electrons, such a mixture of Bosons (bipolarons) and Fermion pairs (pairs of conduction electrons) can undergo an instability towards a superconducting ground state in which at high temperatures the initially localized bipolarons become superfluid upon lowering of the temperature. The experimental situation leading up to such a picture and its physical consequences are discussed.
Introduction
The large values of the critical temperature Tc, the small number of charge carriers together with the short coherence length, the strong dependence of Tc on n/m (n being the carrier concentration and m their mass) and the large temperature regime near Tc (with a Ginzburg temperature of TG 0.1−0.01) controlled by X−Y universality strongly suggest that high-Tc superconductivity is more closely related to Bose–Einstein condensation of real-space pairs than to a BCS state of Cooper pairs. The polaronic nature of at least part of the charge carriers in these materials has been experimentally established in both the insulating and the metallic phase of these compounds. On theoretical grounds one expects small polarons to interact with each other over short distances and in a practically unretarded fashion.
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- Publisher: Cambridge University PressPrint publication year: 1995
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