A Bridge between Ambient- and High-Pressure Superconductivity in Strained Bilayer Nickelate Films

Bilayer nickelates are attracting attention as a new family of high-temperature superconductors. They have a layered crystal structure in which two perovskite layers are stacked together and separated by rock-salt layers (Fig. 1a). Superconductivity has been reported near 80 K in bulk samples under high pressure and near 40 K in strained thin films at ambient pressure. However, the relationship between these two superconducting regimes has remained unclear.

The research team fabricated superconducting La₂LnNi₂O₇ thin films, where Ln is a lanthanide element, and studied how their superconducting properties changed under pressure. Applying pressure increased the superconducting transition temperature from about 40 K at ambient pressure to as high as 67–73 K at 16 GPa, approaching the temperature range previously reported for bulk samples under high pressure. (Fig.1b,c). By comparing this pressure response with changes caused by replacing the Ln element, the researchers found that achieving a higher transition temperature requires careful control not only of the overall lattice size, but also of the balance between the in-plane and out-of-plane lattices and the resulting electronic states. The study experimentally connects ambient- and high-pressure superconductivity within the same thin-film system and provides guidance for designing new high-temperature superconductors.

Fig. 1 | Crystal structure and pressure evolution of superconductivity in bilayer nickelates.

(a) Crystal structure of the bilayer nickelate Ln₃Ni₂O₇, consisting of perovskite bilayers separated by rock-salt layers. (b) Temperature dependence of the normalized resistivity of a La₂SmNi₂O₇ film at 0, 4, and 16 GPa. The superconducting transition shifts to higher temperatures with increasing pressure, and two-step transitions appear at high pressure. (c) Pressure dependence of the superconducting transition temperatures of the La₂SmNi₂O₇ film, compared with previously reported bulk bilayer nickelates [Ref.1. Nature 634, 579–584 (2024)].

Papers 
Journal: Nature Materials
Title: Bridging ambient- and high-pressure superconductivity in La₂LnNi₂O₇ films
Authors: Motoki Osada, Chieko Terakura, Shusaku Imajo, Jean-Baptiste Morée, Akiko Kikkawa, Masamichi Nakajima, Hsiao-Yi Chen, Yusuke Nomura, Koichi Kindo, Ryotaro Arita, Yoshinori Tokura, and Atsushi Tsukazaki
DOI: 10.1038/s41563-026-02695-3