Theoretical study of angle-resolved two-photon photoemission in two-dimensional insulating cuprates

TL;DR

This paper theoretically investigates angle-resolved two-photon photoemission spectroscopy (AR-2PPES) to identify the bottom of the upper Hubbard band in 2D insulating cuprates, providing numerical insights into its spectral features.

Contribution

It introduces a theoretical framework and numerical calculations for AR-2PPES to detect the upper Hubbard band in 2D cuprates, highlighting excitation conditions for clear identification.

Findings

AR-2PPES spectra vary depending on the excitation source.

Exciting the nonbonding oxygen band clearly reveals the UHB bottom.

Additional spectra from spin-wave excitations are observed.

Abstract

We propose angle-resolved two-photon photoemission spectroscopy (AR-2PPES) as a technique to detect the location of the bottom of the upper Hubbard band (UHB) in two-dimensional insulating cuprates. The AR-2PPES spectra are numerically calculated for small Hubbard clusters. When the pump photon excites an electron from the lower Hubbard band, the bottom of the UHB is less clear, but when an electron in the nonbonding oxygen band is excited, the bottom of the UHB can be identified clearly, accompanied with additional spectra originated from the spin-wave excitation at half filling.