Inter-site pair superconductivity: origins and recent validation experiments

Abstract

The challenge of understanding high-temperature superconductivity has led to a plethora of ideas, but 30 years after its discovery in cuprates, very few have achieved convincing experimental validation. While Hubbard and t-J models were given a lot of attention, a number of recent experiments appear to give decisive support to the model of real-space inter-site pairing and percolative superconductivity in cuprates. Systematic measurements of the doping dependence of the superfluid density show a linear dependence on superfluid density - rather than doping - over the entire phase diagram, in accordance with the model's predictions. The doping-dependence of the anomalous lattice dynamics of in-plane Cu-O mode vibrations observed by inelastic neutron scattering, gives remarkable reciprocal space signature of the inter-site pairing interaction whose doping dependence closely follows the predicted pair density. Symmetry-specific time-domain spectroscopy shows carrier localization, polaron formation, pairing and superconductivity to be distinct processes occurring on distinct timescales throughout the entire superconducting phase diagram. The three diverse experimental results confirm non-trivial predictions made more than a decade ago by the inter-site pairing model in the cuprates, remarkably also confirming some of the fundamental notions mentioned in the seminal paper on the discovery of high-temperature superconductivity in cuprates.

Dedicated to Prof. K. A. Mueller on the Occasion of his 90th Birthday

References in corpus (9)

• Inelastic Light Scattering From Correlated Electrons
• The ground state of heavily-overdoped non-superconducting La${}_{2-x}$Sr${}_x$CuO${}_4$
• Evidence for a charge collective mode associated with superconductivity in copper oxides from neutron and x-ray scattering measurements of La${}_{2-x}$Sr${}_x$CuO${}_4$
• Dynamics of broken symmetry nodal and anti-nodal excitations in Bi_{2} Sr_{2} CaCu_{2} O_{8+δ} probed by polarized femtosecond spectroscopy
• Ultrafast carrier localisation in the pseudogap state of cuprate superconductors from coherent quench experiments
• Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy
• Coexistence of excited polarons and metastable delocalized states in photo-induced metals
• Bose-Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors
• Self-organization of charged particles on a 2D lattice subject to anisotropic Jahn-Teller-type interaction and 3D Coulomb repulsion