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 La3Ni2O7 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 La3Ni2O7 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 a pseudogap-like behavior with suppressed spectral weight and diminished quasiparticle peak near E F. Our findings provide important insights into the electronic structure of La3Ni2O7, which will shed light on the understanding of the unconventional superconductivity in nickelates.