Connection between the charge density waves and the superconducting state in the two-Fluid model of superconductivity in HTSC

Abstract

The two-fluid model of superconductivity is used to analyze the physical properties of various HTSCs as a function of different SC gap locations Δ and Δ1 along the energy spectra. In this model, upon doping with oxygen, the charge density waves (CDW) in CuO2 planes, formed in the oxygen anion system, are transformed into local electron pairs (LEPs) by Cu ion oscillations at T*. At Tc < T* the LEPs create a SC state and a gap Δ1. In addition, there is a restructuring of the p- and d-bands. The band gap ΔE decreases. At ΔE ∼ Δ1 the decaying LEPs are transferred from the occupied states of the oxygen anion p-band to the free d-subband of the Cu ions due to thermal excitation. The SC state and the d-type gap Δ in the d-subband can be associated with antiferromagnetic (AF) fluctuations. In tunneling experiments without oxygen anions and oscillating Cu ions, the LEPs undergo strong Coulomb electron repulsion. Therefore, the LEPs and, accordingly, Δ1 will be strongly distorted. This is in contrast to the slight change in the Cooper pairs of conventional superconductors in similar experiments. It seems that the LEPs are transitioning into another state, which can be referred to as the CDW state with a pseudogap Σ. It is also necessary to take into account minor changes in the electron pairs and the second gap Δ created by antiferromagnetic fluctuations.The two-fluid model of superconductivity is used to analyze the physical properties of various HTSCs as a function of different SC gap locations Δ and Δ1 along the energy spectra. In this model, upon doping with oxygen, the charge density waves (CDW) in CuO2 planes, formed in the oxygen anion system, are transformed into local electron pairs (LEPs) by Cu ion oscillations at T*. At Tc < T* the LEPs create a SC state and a gap Δ1. In addition, there is a restructuring of the p- and d-bands. The band gap ΔE decreases. At ΔE ∼ Δ1 the decaying LEPs are transferred from the occupied states of the oxygen anion p-band to the free d-subband of the Cu ions due to thermal excitation. The SC state and the d-type gap Δ in the d-subband can be associated with antiferromagnetic (AF) fluctuations. In tunneling experiments without oxygen anions and oscillating Cu ions, the LEPs undergo strong Coulomb electron repulsion. Therefore, the LEPs and, accordingly, Δ1 will be strongly distorted. This is in contrast to the slight ...