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

TL;DR

This study investigates the electronic structure of La3Ni2O7 at ambient pressure using spectroscopy and calculations, revealing strong correlations and pseudogap behavior that inform understanding of its high-temperature superconductivity.

Contribution

The paper provides the first detailed experimental and theoretical analysis of La3Ni2O7's electronic structure, highlighting correlation effects and pseudogap phenomena relevant to its superconductivity.

Findings

Strong electron correlation pushes a flat band below Fermi level

d_(x^2-y^2) band exhibits pseudogap-like behavior

Experimental results agree with ab-initio calculations after orbital-dependent renormalization

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 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 (EF), which is predicted to locate right at EF 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 EF. Our findings provide important insights into the electronic structure of La3Ni2O7, which will shed light on the understanding of the unconventional superconductivity in nickelates.