Orbital-Selective Superconductivity in Ruddlesden–Popper Nickelates

Recent discoveries of high-temperature superconductivity in the bilayer nickelate La₃Ni₂O₇—both in bulk under high pressure and in thin films at ambient pressure—and related Ruddlesden-Popper nickelates have generated considerable interest in understanding the underlying mechanisms. In this study, we address the effects of orbital-selective electron correlations —where some electronic orbital states experience stronger renormalization effects than others. We show how such effects influence the low-energy electronic structure [1,2] and electronic dynamics [2], and how they drive  the superconducting pairing through both interlayer and intralayer exchange pathways [3]. Our theoretical findings, especially on the orbital-selective effects, compare well with experimental results, including spectroscopic measurements that shed light on the underlying correlation effects in the normal state as well as the measurements on the pairing gap structure in thin films of the bilayer system at ambient conditions. We discuss the implications of these findings for both pressurized bulk La₃Ni₂O₇ and its strain-engineered thin-film counterpart. Multilayer nickelates will also be discussed [4]. 

References:

[1] Z. Liao et al., Electron correlations and superconductivity in La₃Ni₂O₇ under pressure tuning . Phys. Rev. B 108, 214522 (2023).

[2] Z. Liao, Y. Wang et al., Orbital-selective electron correlations in high-Tc bilayer nickelates: from a global phase diagram to implications for spectroscopy. arXiv:2412.21019

[3] G. Duan et al., Orbital-selective correlation effects and superconducting pairing symmetry in a multiorbital t-J model for bilayer nickelates. arXiv:2502.09195

[4] K-S Lin, Y. Wang et al., to be published (2025)