Signatures of ambient pressure superconductivity in thin film La₃Ni₂O₇

The bilayer nickelate, La₃Ni₂O₇, has been discovered as a new superconductor with a transition temperature (T_c) near 80 K under high pressure¹. However, such pressure requirement limits experimental techniques and practical applications. Here, we report superconductivity in compressively strained La₃Ni₂O₇ thin films at ambient pressure. The onset T_c ranges from 26 K to 42 K, and higher T_c linked to smaller in-plane lattice constants. Additionally, we found that transport properties are affected by ozone annealing and observed co-existing Ruddlesden-Popper phases in the films. Therefore, we suggest that the low zero-resistance T_c of approximately 2 K in the films is due to stacking defects, grain boundaries, and oxygen stoichiometry. The detailed structural characteristics of the films and their relationship to superconductivity will be addressed.



[1] Sun, H. et al. Signatures of superconductivity near 80 K in a nickelate under high pressure. Nature 621, 493–498 (2023).