Comparative study of the superconductivity in the Holstein and optical Su-Schrieffer-Heeger models

Journal Article · Wed Nov 01 00:00:00 EDT 2023 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.108.184501· OSTI ID:2216887

Ly, Andy Tanjaroon ^[1]; Cohen-Stead, Benjamin ^[2]; Costa, Sohan Malkaruge ^[2]; Johnston, Steven ^[2]

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1. University of Tennessee, Knoxville, TN (United States); University of Tennessee, Knoxville
2. University of Tennessee, Knoxville, TN (United States)

Theoretical studies suggest that Su-Schrieffer-Heeger-like electron-phonon (e-ph) interactions can mediate high-temperature bipolaronic superconductivity that is robust against repulsive electron-electron interactions. Here we present a comparative analysis of the pairing and competing charge/bond correlations in the two-dimensional Holstein and optical Su-Schrieffer-Heeger (SSH) models using numerically exact determinant quantum Monte Carlo. We find that the SSH interactions support light bipolarons and strong superconducting correlations out to relatively large values of the e-ph coupling λ and densities near half-filling, while the Holstein interaction does not due to the formation of heavy bipolarons and competing charge-density-wave order. We further find that the Holstein and SSH models have comparable pairing correlations in the weak coupling limit for carrier concentrations < n > <<1, where competing orders and polaronic effects are absent. These results support the proposal that SSH (bi)polarons can support superconductivity to larger values of λ in comparison to the Holstein polaron, but that the resulting T_c gains are small in the weak coupling limit. We also find that the SSH model's pairing correlations are suppressed after including a weak on-site Hubbard repulsion. Furthermore, these results have important implications for identifying and engineering bipolaronic superconductivity.

• Research Organization: University of Tennessee, Knoxville, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC05-00OR22725; SC0022311
• OSTI ID: 2216887
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 18 Vol. 108; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Holstein model
Su-Schrieffer-Heeger model
Superconductivity