Influence of spin fluctuations on the superconducting transition temperature and resistivity in the t-J model at large N

Abstract

Spin fluctuations enter the calculation of the superconducting transition temperature T${}_c$ only in the next-to-leading order (i.e., in O(1/N${}^2$) of the 1/N expansion of the t-J model. We have calculated these terms and show that they have only little influence on the value of T${}_c$ obtained in the leading order O(1/N) in the optimal and overdoped region, i.e., for dopings larger than the instability towards a flux phase. This result disagrees with recent spin-fluctuation mediated pairing theories. The discrepancies can be traced back to the fact that in our case the coupling between electrons and spins is determined by the t-J model and not adjusted and that the spin susceptibility is rather broad and structureless and not strongly peaked at low energies as in spin-fluctuation models. Relating T${}_c$ and transport we show that the effective interactions in the particle-particle and particle-hole channels are not simply related within the 1/N expansion by different Fermi surface averages of the same interactin as in the case of phonons or spin fluctuations. As a result, we find that large values for T${}_c$ and rather small scattering rates in the normal state as found in the experiments can easily be reconciled with each other. We also show that correlation effects heavily suppress transport relaxation rates relative to quasiparticle relaxation rates in the case of phonons but not in the case of spin fluctuations.

16 pages, 10 figures, will appear in Phys. Rev. B

References in corpus (4)

• Coupling strength of charge carriers to spin fluctuations in high-temperature superconductors
• Quantum Impurities and the Neutron Resonance Peak in $\mathbf{YB}{\mathbf{a}}_2\mathbf{C}{\mathbf{u}}_3{\mathbf{O}}_7$: Ni versus Zn
• Electronic correlations, electron-phonon interaction, and isotope effect in high-Tc cuprates
• Violation of Luttinger's theorem in strongly correlated electronic systems within a 1/N expansion

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• Collective excitations in unconventional charge-density wave systems
• Manifestation of marginal Fermi liquid and phonon excitations in photoemision experiments of cuprate superconductors
• Self-energy effects in cuprates and the dome-shaped behavior of the superconducting critical temperature