Emergence of Quasiparticles in a Doped Mott Insulator

TL;DR

This study investigates how doping transforms a Mott insulator into a metal, revealing the emergence of quasiparticles and spectral features, and assesses the Hubbard model's effectiveness in describing high-temperature superconductor behavior.

Contribution

It provides a detailed analysis of the evolution of quasiparticles and spectral features in doped Mott insulators using cluster perturbation theory, benchmarking the Hubbard model against ARPES data.

Findings

Quasiparticle dispersion develops immediately across the Fermi level at low doping.

Spectral weight grows roughly twice as fast as doping at low levels, halving at optimal doping.

Persistent Mott spectral features and electron-hole asymmetry are observed in heavily doped regimes.

Abstract

How a Mott insulator develops into a weakly coupled metal upon doping is a central question to understanding various emergent correlated phenomena. To analyze this evolution and its connection to the high-$T_c$ cuprates, we study the single-particle spectrum for the doped Hubbard model using cluster perturbation theory on superclusters. Starting from extremely low doping, we identify a heavily renormalized quasiparticle dispersion that immediately develops across the Fermi level, and a weakening polaronic side band at higher binding energy. The quasiparticle spectral weight roughly grows at twice the rate of doping in the low doping regime, but this rate is halved at optimal doping. In the heavily doped regime, we find both strong electron-hole asymmetry and a persistent presence of Mott spectral features. Finally, we discuss the applicability of the single-band Hubbard model to describe the evolution of nodal spectra measured by angle-resolved photoemission spectroscopy (ARPES) on the single-layer cuprate La$_{2-x}$Sr$_x$CuO$_4$ ($0 \le x \le 0.15$). This work benchmarks the predictive power of the Hubbard model for electronic properties of high-$T_c$ cuprates.