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

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 La 3 Ni 2 O 7 at high pressure, which provides a new platform to explore the unconventional HTSC. In this work, using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation, we systematically investigate the electronic structures of La 3 Ni 2 O 7 at ambient pressure. Our experiments are in nice agreement with ab initio calculations after considering an orbital-dependent band renormalization effect. The strong electron correlation effect pushes a flat band of d z 2 orbital component below the Fermi level ( E F ), which is predicted to locate right at E F under high pressure. Moreover, the d x 2 – y 2 band shows pseudogap-like behavior with suppressed spectral weight and diminished quasiparticle peak near E F . Our findings provide important insights into the electronic structure of La 3 Ni 2 O 7 , which will shed light on understanding of the unconventional superconductivity in nickelates.