Matrix Element and Strong Electron Correlation Effects in ARPES from Cuprates

TL;DR

This paper investigates how ARPES matrix elements and strong electron correlations influence spectral intensities in cuprates, revealing selectivity effects and the evolution of the Fermi surface with doping, including the collapse of the Mott pseudogap.

Contribution

It provides new insights into the effects of ARPES matrix elements and strong correlations on spectral features, and models Fermi surface evolution in doped cuprates using the Hubbard model.

Findings

ARPES matrix element exhibits selectivity, enhancing specific states.

Fermi surface emission at low photon energies is dominated by oxygen atoms.

Mott pseudogap collapses near optimal doping, indicating a quantum critical point.

Abstract

We discuss selected results from our recent work concerning the ARPES (angle-resolved photoemission) spectra from the cuprates. Our focus is on developing an understanding of the effects of the ARPES matrix element and those of strong electron correlations in analyzing photointensities. With simulations on Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212), we show that the ARPES matrix element possesses remarkable selectivity properties, such that by tuning the photon energy and polarization, emission from the bonding or the antibonding states can be enhanced. Moreover, at low photon energies (below 25 eV), the Fermi surface (FS) emission is dominated by transitions from just the O-atoms in the CuO$_2$ planes. In connection with strong correlation effects, we consider the evolution with doping of the FS of Nd$_{2-x}$Ce$_x$CuO$_{4\pm\delta}$ (NCCO) in terms of the $t$-$t'$-$U$ Hubbard model Hamiltonian. We thus delineate how the FS evolves on electron doping from the insulating state in NCCO. The Mott pseudogap is found to collapse around optimal doping suggesting the existence of an associated quantum critical point.