Kinetic-energy-driven superconductivity in cuprate superconductors (Q2809462)

The paper presents a review of the kinetic-energy-driven superconductivity (KED SC) mechanism and summarizes several calculated results of physical quantities obtained on the base of the mechanism. First, the fermion-spin theory is treated, the constrained electron is decoupled as a product of gauge invariant charge carrier and a localized spin with the charge carrier keeping track of the charge degree of freedom together with some effects of the spin configuration rearrangements due to the presence of the doped charge carrier itself. Then the KED SC mechanism is introduced, where the effective attractive interaction between charge carriers originates in their coupling to spin excitations serving as the pairing glue. This KED SC state is conventional BCS-like with the \(d\)-wave symmetry. It is shown how this KED SC mechanism yields many results that are in wide agreement with various key experimental facts observed in cuprate superconductors. Then, this mechanism is applied to the discussion of the Meissner effect in cuprate superconductors. Main features of the doping dependence of the electromagnetic response observed on cuprate superconductors are considered by using the muon-spin rotation measurement technique and they are shown to be similar to the dome-like shape of the doping dependence of the critical temperature, the maximal superfluid density occurs around the critical doping and then decreases in both lower-doped and higher-doped regimes. The authors summarize a few calculated results for the dynamical spin response of cuprate superconductors. These results are compared with the resonant inelastic X-ray scattering (RIXS) -- inelastic neutron scattering (INS) experimental data. The low-energy spin excitations in the SC-state have an hour-glass-shaped dispersion, with commensurate resonance that appears in the SC-state only, while the low-energy incommensurate spin fluctuations can persist into the normal state. The high-energy spin excitations in the SC-state retain roughly constant the energy as a function of doping with spectral weights and dispersion relations comparable to those found in the parent compounds. Then the microscopic theory of the normal-state pseudogap state is reviewed. It is shown that the same charge-carrier interaction arising through the exchange of spin excitations that generates the SC-state in the particle-particle channel also induces the normal-state pseudogap state in the particle-hole channel, indicating that the spin excitation plays a decisive role in the formation of both the SC-state and the normal-state pseudogap-state. Then the effect of the normal-state pseudogap on the infrared response of cuprate superconductors is discussed. The authors show that in the underdoped and optimally doped regimes, the transfer of the part of the low-energy spectral weight of the conductivity spectrum to the higher-energy region to form a mid infrared band is intrinsically associated with the emergence of the normal-state pseudogap.