Fluctuating Cu-O-Cu Bond model of high temperature superconductivity in cuprates

TL;DR

This paper proposes a fluctuating Cu-O-Cu bond model within a Fermi liquid framework that explains key features of high-temperature superconductivity in cuprates, emphasizing oxygen vibrations and bond modulation.

Contribution

It introduces a novel anharmonic mechanism based on oxygen vibrational amplitude modulating Cu-Cu bonds, providing a unified explanation for HTS characteristics.

Findings

Explains d-wave pairing via oxygen vibrational modulation.

Accounts for pseudogap and isotope effects.

Aligns with observed inhomogeneity and Fermi liquid behavior.

Abstract

Twenty years of extensive research has yet to produce a general consensus on the origin of high temperature superconductivity (HTS). However, several generic characteristics of the cuprate superconductors have emerged as the essential ingredients of and/or constraints on any viable microscopic model of HTS. Besides a Tc of order 100K, the most prominent on the list include a d-wave superconducting gap with Fermi liquid nodal excitations, a d-wave pseudogap with the characteristic temperature scale T*, an anomalous doping-dependent oxygen isotope shift, nanometer-scale gap inhomogeneity, etc.. The key role of planar oxygen vibrations implied by the isotope shift and other evidence, in the context of CuO2 plane symmetry and charge constraints from the strong intra-3d Coulomb repulsion U, enforces an anharmonic mechanism in which the oxygen vibrational amplitude modulates the strength of the in-plane Cu-Cu bond. We show, within a Fermi liquid framework, that this mechanism can lead to strong d-wave pairing and to a natural explanation of the salient features of HTS.