2025/07/10 by Wenjie Sun, Zhicheng Jiang, Sun, Wenjie +25
Materials Science · #Electronic and Structural Properties of Oxides #FOS: Physical sciences #Iron-based superconductors research #Magnetic and transport properties of perovskites and related materials #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.2507.07409
openalex publication_date 2025/07/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The discovery of high-temperature superconductivity in pressurized bulk La3Ni2O7 has ignited significant interest in nickelate superconductors. Unlike cuprates, where superconductivity predominantly originates from the 3dx2-y2 orbital, nickelates exhibit additional complexities involving contributions from the 3dz2 orbital, prompting fundamental questions about their pairing mechanisms. Despite recent progress in stabilizing superconductivity in La3Ni2O7 thin films at ambient pressure, direct spectroscopic evidence of the superconducting gap opening remains elusive. Here, we present an in-situ angle-resolved photoemission spectroscopy study of Sr-doped superconducting La3Ni2O7 thin films. Fermi surface mapping reveals Ni-3dx2-y2-derived α and β pockets, with orbital fillings of 0.11±0.02 electrons and 0.66±0.03 holes per Ni, respectively, resulting in a total of 0.45±0.04 electrons for each Ni. These bands exhibit moderate electron correlations, characterized by a band renormalization factor of 3-4. Notably, both α and β bands exhibit leading-edge shifts across the superconducting transition, with gap magnitude of ~1-2 meV at Fermi momenta along the Brillouin zone diagonal and slightly away from the zone diagonal, deviating from the conventional dx2-y2-wave gap structure. Additionally, the Ni-3dz2-derived γ band lies ~75 meV below the Fermi level, indicating a 3dx2-y2-dominated fermiology in this compound.