High-temperature superconducting dome mapped in nickelate thin films

A recent study has successfully mapped the high-temperature superconducting dome in thin films of the nickelate compound La₃Ni₂O₇, marking a significant advance in understanding superconductivity in this emerging family of materials. Nickelates have garnered attention due to their structural similarity to cuprates, known for record high-temperature superconductivity, but a detailed phase diagram showing how electronic states evolve with doping and temperature had been lacking. By precisely growing ultrathin La₃Ni₂O₇ films using reactive molecular beam epitaxy and applying strain engineering, researchers created high-quality samples suitable for detailed investigation. The team tuned the material’s electronic properties through two main methods: substituting lanthanum atoms with strontium (doping) and adjusting oxygen content via vacuum annealing to create oxygen vacancies. These approaches allowed fine control over the charge carrier concentration, analogous to techniques used in cuprate superconductors. Electrical measurements, including tracking the Hall coefficient to infer carrier type and density, enabled the