A weakly correlated Fermi liquid state with a small Fermi surface in lightly doped Sr$_3$Ir$_2$O$_7$

TL;DR

This study uses angle-resolved photoemission to reveal a weakly correlated Fermi liquid state with a small Fermi surface in lightly doped Sr$_3$Ir$_2$O$_7$, showing coherent quasiparticles and moderate renormalization.

Contribution

It provides the first detailed characterization of the Fermi surface and quasiparticle properties in lightly doped Sr$_3$Ir$_2$O$_7$, demonstrating a conventional Fermi liquid behavior.

Findings

Emergence of a small Fermi surface with volume proportional to doping level

Large quasiparticle weight Z indicating weak correlations

Fermi liquid behavior with moderate dispersion renormalization

Abstract

We characterize the electron doping evolution of (Sr$_{1-x}$La$_x$)$_3$Ir$_2$O$_7$ by means of angle-resolved photoemission. Concomitant with the metal insulator transition around $x\approx0.05$ we find the emergence of coherent quasiparticle states forming a closed small Fermi surface of volume $3x/2$, where $x$ is the independently measured La concentration. The quasiparticle weight $Z$ remains large along the entire Fermi surface, consistent with the moderate renormalization of the low-energy dispersion. This indicates a conventional, weakly correlated Fermi liquid state with a momentum independent residue $Z\approx0.5$ in lightly doped Sr$_3$Ir$_2$O$_7&.