Work

s ± pairing symmetry from electron-phonon coupling in La 3 Ni 2 O 7 under pressure

Year: 2025

Type: article

Abstract: The recently discovered bilayer Ruddlesden-Popper nickelate ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ exhibits superconductivity with a remarkable transition temperature ${T}_{c}\ensuremath{\approx}80$ K under applied pressures above 14.0 GPa. This discovery of a new family of high-temperature superconductors has garnered significant attention in the condensed matter physics community. In this work, we assume this high-temperature superconductor is mediated by phonons and investigate the pairing symmetry in two distinct models: (i) the full-coupling case, where the Ni-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and Ni-${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbitals are treated equally in both interlayer and intralayer coupling interactions, and (ii) the half-coupling case, where the intralayer coupling involves only the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbital, while the interlayer coupling is restricted to the ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbital. Our calculations reveal that the interlayer coupling favors an $s\ifmmode\pm\else\textpm\fi{}$-wave superconducting state, whereas the intralayer coupling promotes an $s++$-wave symmetry. Additionally, we discuss the implications of pair-hopping interactions on the superconducting properties. These findings provide valuable insights into the pairing mechanisms and symmetry of this newly discovered high-temperature superconductor.

Source: Physical review. B./Physical review. B

DOI: 10.1103/sg46-ct3y

Authors: Yucong Yin, Jun Zhan, Boyang Liu, Xinloong Han