Source capture
Authors Jun-jie Shi, Yao-hui Zhu
arXiv / Publisher https://arxiv.org/abs/2503.13104
PDF https://arxiv.org/pdf/2503.13104
Relevance score 4.711
Primary category cond-mat.supr-con
Published 2026-03-11
Research paradigm Theoretical
Sample form Unknown

Summary

Addressing the long-standing puzzle of the pairing mechanism for high-temperature superconductivity in cuprates and nickelates, this paper proposes a picture of itinerant Cooper pairs mediated by oxygen-bridged electron pairs (e--O-e-) or metal-bridged hole pairs (h+-M-h+), based on the dominant role of ionic bonds on the order of eV, the electron affinities of O- and O2- (1.46 eV and -8.08 eV, respectively), and the large double ionization energies of metal atoms (approximately 15–28 eV). Such pairing forms below the pseudogap temperature T*, which is higher than Tc, and follows the relationship of chemical bond → structure → properties, being applicable to cuprates, nickelates, iron-based, and other ionic superconductors. The author verifies the correctness and universality of this mechanism through 32 independent experimental pieces of evidence, especially STM images within the CuO2 plane and the extremely small pairing size, and points out that any sub-eV or covalent bonding pairing mechanism is unreliable. This theory reveals the missing link between ionic bonds and superconductivity, resolves a four-decade-long puzzle, and demonstrates the feasibility of achieving room-temperature carrier pairing in ionic-bond superconductors. Based on this, the author establishes a new theoretical framework centered on the strongest pairing strength and Bose–Einstein condensation, opening a new path for understanding the mechanism of high-temperature superconductivity and bringing the dream of room-temperature superconductivity closer to reality.

Materials

Methods

  • theoretical analysis based on ionic bonding
  • charge sum rule
  • comparison with STM images
  • calculation of screened Coulomb repulsion

Keywords

  • ionic bond
  • cooper pair
  • oxygen bridged pairing
  • metal bridged pairing
  • pseudogap
  • bose einstein condensation
  • d wave symmetry
  • charge stripe
  • room temperature superconductivity

Highlights

  • This mechanism is applicable to cuprates, nickelates, iron-based and other new ionic superconductors.
  • The STM image in the CuO2 plane combining with the small pair size serves as an ironclad proof.
  • Any other sub-eV and covalent-binding pairing mechanisms would be doubtful.
  • The theory reveals that room-temperature Cooper pairing is feasible in ionic-bonded superconductors.

Conclusions

  • We propose an innovative idea of electron e- (hole h+) pairing bridged by oxygen O (metal M) atoms, i.e., the ionic-bond-driven e- -O- e- (h+ -M- h+) itinerant Cooper pairing.
  • Its correctness and universality are confirmed by 32 diverse experimental evidences.
  • Our findings provide the missing link between ionic bonding and superconductivity, resolve a 40-year puzzle and validate the feasibility of room-temperature carrier-pairing in ionic superconductors.

Main claims

  • Ionic-bond-driven oxygen-bridged electron pairs (e--O-e-) and metal-bridged hole pairs (h+-M-h+) are the universal Cooper pairing mechanism in cuprates, nickelates, and other ionic superconductors.
    • Evidence: abstract: 'we propose a groundbreaking idea of electron e- (hole h+) pairing bridged by oxygen O (metal M) atoms',full_text: 'the ionic-bond-driven e--O-e- (h+-M-h+) itinerant Cooper pairing formed at pseudogap temperature T* > Tc'
  • The proposed pairing mechanism is supported by 32 diverse experimental evidences, especially STM images of hole stripes along Cu-O-Cu chains and small Cooper pair size.
    • Evidence: abstract: 'correctness and universality are confirmed by 32 diverse experimental evidences, especially, the STM image in the CuO2 plane combining with the small Cooper-pair size',full_text Fig. 4a shows STM constant-current topographic image of hole stripe phase
  • Any sub-eV pairing mechanism (e.g., magnetic or electron-phonon) cannot overcome the eV-scale Coulomb repulsion between two holes in a Cooper pair; eV-scale ionic bonds are required.
    • Evidence: full_text Fig. 3 shows calculated screened Coulomb repulsion ≈2.63 eV for two holes at 1.5 Å,abstract: 'Any other sub-eV and covalent-binding pairing mechanisms would be doubtful'
  • The eV-scale ionic bonding enables Cooper pair formation above Tc or even at room temperature, potentially enabling room-temperature superconductivity if coherent condensation is achieved.
    • Evidence: full_text: 'the eV-scale ionic bonds… ensure that Cooper pairs can be formed above Tc or even at room temperature',abstract: 'validate the feasibility of room-temperature carrier-pairing in ionic-bonded superconductors'

Workflow

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