Progress of ambient-pressure superconductivity in bilayer nickelate thin films

Abstract

This review summarizes recent progress of ambient-pressure superconductivity in bilayer nickelate La$_3$Ni$_2$O$_7$ thin films, a major advancement following the discovery of high-pressure superconductivity in bulk La$_3$Ni$_2$O$_7$. First, we explain how epitaxial strain engineering enables ambient-pressure superconductivity in La$_3$Ni$_2$O$_7$ thin films, with compressive strain from substrates like SrLaAlO$_4$ stabilizing superconductivity. Next, we review experimental characterizations of related systems, with particular emphasis on ARPES measurements that have shown conflicting Fermi surface topologies. We then discuss progress in increasing the superconducting transition temperature $T_c$. Finally, we summarize theoretical studies of the electronic structure and pairing symmetry of La$_3$Ni$_2$O$_7$ thin films. Together, these advances establish bilayer nickelate thin films as a highly tunable and promising platform for exploring high-$T_c$ superconductivity.

Figures (6)

• Figure 1: Microscopic structures of (a) La$_{2.85}$Pr$_{0.15}$Ni$_2$O$_7$ sample on SrLaAlO$_4$Zhouambient-pressure2025 and (b) of La$_3$Ni$_2$O$_7$ on SrLaAlO$_4$Kosignatures2025.
• Figure 2: (a) Temperature-dependent resistivity $\rho$(T) of La$_3$Ni$_2$O$_7$ thin films grown on different substrates Kosignatures2025. (b)FS of La$_{2.85}$Pr$_{0.15}$Ni$_2$O$_7$ thin films, consisting of $\alpha$, $\beta$ and $\gamma$ pockets Liangle2025. (c) FS of La$_{2}$PrNi$_2$O$_7$ thin films, without $\gamma$ pocket appearing on FS Wangelectronic2025. (d) Measured superconducting gap magnitudes on the $\beta$ and $\gamma$ bands as a function of the angle $\theta$Shennodeless2025.
• Figure 3: FS Nieambient2025 of thin films grown on SLAO substrates measured by ARPES for (a) 1212 structure, (b) 2222 structure, (c) 1313 structure and (d) bulk La$_3$Ni$_2$O$_7$.
• Figure 4: (a) The energy bands and (c) FS of La$_3$Ni$_2$O$_7$ thin films, combining DFT and DMFT Yuecorrelated2025. (b) The energy bands and (d) FS of the One-UC double-stack tight-binding model for La$_3$Ni$_2$O$_7$ thin films Huelectronic2025.
• Figure 5: (a) The leading cRPA calculated gap functions on the FS and (b) the dependence of $\lambda$ on $U_{eff}$Yuecorrelated2025. (c) The leading RPA calculated gap functions on the FS and (d) the dependence of $\lambda$ on $U$ without $\gamma$ pocket Shaopairing2025.