One-step approach to ARPES from strongly correlated solids: a Mott-Hubbard system

TL;DR

This paper derives a direct method to analyze ARPES data from strongly correlated materials, linking photocurrent to Green's functions and surface effects, with applications to Mott-Hubbard systems.

Contribution

It introduces an analytical expression connecting surface-sensitive ARPES measurements to bulk Green's functions in strongly correlated solids.

Findings

Photocurrent is proportional to the spectral function of a localized surface state.

The momentum dependence reveals quasiparticle and incoherent spectral features.

Surface and final state effects significantly influence ARPES spectra.

Abstract

An expression is derived for angle-resolved photocurrent from a semi-infinite correlated system. Within the sudden approximation, the photocurrent is proportional to the spectral function of a one-particle two-time retarded Green's function $\mathcal{G}$ of an operator that creates an electron in a special quantum state $\chi$ localized at the surface. For a system described by a many-body single-band model we present an analytical expression that relates the Green's function $\mathcal{G}$ with the Green's function of an infinite crystal $G_{b,\mathbf{k}}(\omega)$ in Wannier representation. The role of final states and of the crystal surface is analysed for a model Green's function of the infinite crystal with a three-peak spectral function typical of a Mott-Hubbard metal. The momentum dependence of both the quasiparticle pole position and the spectral weight of the incoherent band manifest themselves in the shape of the photocurrent energy distribution curve.