Pressure induced superconductivity in hybrid Ruddlesden‒Popper La5Ni3O11 single crystals

The discovery of high-temperature superconductivity under high pressure in Ruddlesden–Popper phase nickelates has captured notable attention in the condensed matter physics community. Here we report superconductivity in a distinct hybrid nickelate, La₅Ni₃O₁₁, formed by alternating stacks of La₃Ni₂O₇ and La₂NiO₄ layers. This nickelate also exhibits a density-wave transition at approximately 170 K near ambient pressure. With increasing pressure, this density-wave transition shifts to higher temperatures and abruptly disappears around 12 GPa, followed by the emergence of superconductivity, indicating a first-order phase transition. But the optimal superconductivity with large superconducting volume fraction is observed at approximately 21 GPa with \({T}_{{\rm{c}}}^{{\;\rm{zero}}}\) = 54 K. High-pressure X-ray diffraction experiments reveal a structural phase transition from an orthorhombic structure to a tetragonal structure at lower pressure. Notably, this structural change has minimal impact on the density-wave or superconducting phases, suggesting a limited role of lattice degrees of freedom in this material. These findings establish La₅Ni₃O₁₁ as a new superconducting member of the Ruddlesden–Popper nickelate family and offer valuable insights into the interplay between structure, electronic order and superconductivity in hybrid nickelates.