Electronic Correlation and Pseudogap-Like Behavior of High-Temperature Superconductor La₃Ni₂O₇

Abstract High-temperature superconductivity (HTSC) remains one of the most challenging and fascinating mysteries in condensed matter physics. Recently, superconductivity with transition temperature exceeding liquid-nitrogen temperature is discovered in La₃Ni₂O₇ at high pressure, which provides a new platform to explore the unconventional HTSC. In this work, using high-resolution angle-resolved photoemission spectroscopy andab initiocalculation, we systematically investigate the electronic structures of La₃Ni₂O₇ at ambient pressure. Our experiments are in nice agreement withab initiocalculations after considering an orbital-dependent band renormalization effect. The strong electron correlation effect pushes a flat band ofd_z² orbital component below the Fermi level (E_F), which is predicted to locate right atE_F under high pressure. Moreover, thed_x²–y² band shows pseudogap-like behavior with suppressed spectral weight and diminished quasiparticle peak nearE_F. Our findings provide important insights into the electronic structure of La₃Ni₂O₇, which will shed light on understanding of the unconventional superconductivity in nickelates.