Robust d-wave superconductivity from the Su-Schrieffer-Heeger-Hubbard model: possible route to high-temperature...

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Computational Physics

Background:

• The simplest Hubbard model with strong repulsion often fails to explain high-temperature superconductivity (SC).
• Exploring alternative microscopic mechanisms for high-temperature SC is crucial for materials science.
• Understanding the interplay of different interactions is key to discovering novel superconducting states.

Purpose of the Study:

• To investigate the combined effects of Su-Schrieffer-Heeger (SSH) electron-phonon coupling (EPC) and Hubbard repulsion on superconductivity.
• To determine if this interplay can lead to high-temperature SC.
• To elucidate the role of SSH-type EPC in generating magnetic interactions that promote SC.

Main Methods:

• Utilizing state-of-the-art density-matrix-renormalization-group (DMRG) simulations.
• Analyzing the Hubbard model on a square lattice incorporating SSH electron-phonon coupling.
• Investigating the phase diagram for varying strengths of Hubbard repulsion (U) and SSH EPC (λ).

Main Results:

• The interplay between strong Hubbard repulsion (U) and moderate SSH EPC (λ) robustly induces d-wave SC.
• SSH-type EPC generates effective antiferromagnetic spin-exchange interactions, crucial for SC.
• A critical SSH EPC value (λ_c = 0.1-0.2) was identified for U=8t to achieve d-wave SC.

Conclusions:

• The combination of strong Hubbard U and moderate SSH λ offers a viable mechanism for high-temperature SC.
• This finding provides new insights into SC in cuprates and suggests routes for discovering SC in other quantum materials.
• The study highlights the importance of electron-phonon coupling in realizing exotic electronic states.