Multiband Effects on Superconducting Instabilities Driven by Electron-Electron Interactions

Abstract

We explore multiband effects on d-wave superconducting instabilities driven by electron-electron interactions. Our models on the two-dimensional square lattice consist of a main band with an extended Fermi surface and predominant weight from $d_{x^2-y^2}$ orbitals, whose orbital character is influenced by the admixture of other energetically neighbored orbitals. Using a functional renormalization group description of the superconducting instabilities of the system and different levels of approximations, we study how the energy scale for pairing and hence the critical temperature is affected by the band structure. We find that a reduction of orbital admixture as a function of the orbital energies can cause a $T_c$ enhancement although the Fermi surface becomes more curved and hence less favorable for antiferromagnetic spin fluctuations. While our study does not allow a quantitative understanding of the $T_c$ differences in realistic high-$T_c$ cuprate systems, it may reveal an underlying mechanism contributing to the actual material trends.

12 pages, 8 figures, additional interaction terms in section IV and VI included, amended discussion and plots, additional minor changes

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• Quasiparticle self-consistent GW study of cuprates: electronic structure, model parameters, and the two-band theory for Tc
• Effective interactions in multi-band systems from constrained summations
• Multiorbital effects in the functional renormalization group: A weak-coupling study of the Emery model
• Unified description of cuprate superconductors using four-band $d$-$p$ model
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• Superconducting dome with $extended$ $s$-$wave$ pairing symmetry in the heavily hole-overdoped copper-oxide planes
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• First-principles band structure and FLEX approach to the pressure effect on $T_c$ of the cuprate superconductors
• Three-orbital study on the orbital distillation effect in the high Tc cuprates
• Response Theory of the Electron-Phonon Coupling