Recently, the bilayer nickelate La₃Ni₂O₇ has been discovered as a new superconductor with transition temperature T_c near 80 K under high pressure^1–3. Despite extensive theoretical and experimental work to understand the nature of its superconductivity^4–29, the requirement of extreme pressure restricts the use of many experimental probes and limits its application potential. Here, we present signatures of superconductivity in La₃Ni₂O₇ thin films at ambient pressure, facilitated by the application of epitaxial compressive strain. The onset T_c varies approximately from 26 K to 42 K, with higher T_c values correlating with smaller in-plane lattice constants. We observed the co-existence of other Ruddlesden-Popper phases within the films and dependence of transport behavior with ozone annealing, suggesting that the observed low zero resistance T_c of around 2 K can be attributed to stacking defects, grain boundaries, and oxygen stoichiometry. This finding initiates numerous opportunities to stabilize and study superconductivity in bilayer nickelates at ambient pressure, and to facilitate the broad understanding of the ever-growing number of high temperature and unconventional superconductors in the transition metal oxides.

最近，双层镍酸盐 La₃Ni₂O₇ 被发现是一种新型超导体，在高压^1-3 下转变温度 TC_接近 80 K。尽管有大量的理论和实验工作来了解其超导性^{的性质 4-29}，但极压的要求限制了许多实验探针的使用并限制了其应用潜力。在这里，我们展示了在环境压力下 La₃Ni₂O₇ 薄膜的超导特性，这得益于外延压缩应变的应用。起始 T_c 大约在 26 K 到 42 K 之间变化，较高的 T_c 值与较小的面内晶格常数相关。我们观察到薄膜内其他 Ruddlesden-Popper 相共存，并且输运行为与臭氧退火的依赖性，这表明观察到的约 2 K 的低零电阻 T_c 可归因于堆叠缺陷、晶界和氧化学计量。这一发现为稳定和研究环境压力下双层镍酸盐的超导性提供了许多机会，并促进了对过渡金属氧化物中不断增长的高温和非常规超导体的广泛理解。