Electronic Structure of Kinetic Energy Driven Cuprate Superconductors

Abstract

In this paper, we review the low energy electronic structure of the kinetic energy driven d-wave cuprate superconductors. We give a general description of the chargespin separation fermion-spin theory, where the constrained electron is decoupled as the gauge invariant dressed holon and spin. In particular, we show that under the decoupling scheme, the charge-spin separation fermion-spin representation is a natural representation of the constrained electron defined in a restricted Hilbert space without double electron occupancy. Based on the charge-spin separation fermionspin theory, we have developed the kinetic energy driven superconducting mechanism, where the superconducting state is controlled by both superconducting gap parameter and quasiparticle coherence. Within this kinetic energy driven superconductivity, we have discussed the low energy electronic structure of the single layer and bilayer cuprate superconductors in both superconducting and normal states, and qualitatively reproduced all main features of the angle-resolved photoemission spectroscopy measurements on the single layer and bilayer cuprate superconductors. We show that the superconducting state in cuprate superconductors is the conventional Bardeen-Cooper-Schrieffer like with the d-wave symmetry, so that the basic Bardeen-Cooper-Schrieffer formalism with the d-wave gap function is still valid in discussions of the low energy electronic structure of cuprate superconductors, although the pairing mechanism is driven by the kinetic energy by exchanging spin excitations. We also show that the well pronounced peak-dip-hump structure of the bilayer cuprate superconductors in the superconducting state and double-peak structure in the normal state are mainly caused by the bilayer splitting.

Kinetic-energy-driven superconductivity in cuprate superconductors

“…In this case, three basic low-energy excitations for the charge-carrier quasiparticles, the spin excitations and the electron quasiparticles, respectively, emerge as the propagating modes in a doped Mott the spin response, while as a result of the charge-spin recombination, the electron quasiparticles govern the electronic properties. [119][120][121][122] 2.6. Fermion-spin representation: A natural representation for constrained electron…”

“…122 In Eq. (5), the constrained electron operatorsC † lσ andC lσ are expressed in terms of the unconstrained electron operators C † lσ and C lσ asC † lσ = C † lσ (1 − n l−σ ) andC lσ = C lσ (1 − n l−σ ), respectively.…”

“…In the fermionspin theory, although both charge carriers and spins contribute to the charge dynamics, the results in Eqs. (117) and (122) show that the anomalous conductivity properties are mainly caused by charge carriers, [236][237][238][239] which are strongly renormalized because of the strong interaction with the fluctuation of the surrounding spin excitations, and then the low-energy spectral weight of the conductivity spectrum is proportional to the charge-carrier doping concentration δ. 226,227…”

“…(122) in the normal-state has been calculated [236][237][238] and the result 238 of σ(ω) as a function of energy at δ = 0.09 (solid line), δ = 0.15 (dashed line) and δ = 0.25 (dotted line) with T = 0.002J for t/J = 2.5 and t ′ /t = 0.3 is shown in Fig. 27, hereafter in this section we set the charge e and reduced Planck constant as the unity.…”

Dynamical spin response of electron doped Mott insulators on a triangular lattice

“…, in the charge-spin separation fermion-spin theory 22,23 , where the spinful fermion operator a iσ = e −iΦiσ a i describes the charge degree of freedom together with some effects of the spin configuration rearrangements due to the presence of the doped electron itself (charge carrier), while the spin operator S i describes the spin degree of freedom (spin), then the single occupancy local constraint,…”