Theory of Core-Level Photoemission and the X-ray Edge Singularity Across the Mott Transition

TL;DR

This paper investigates the core-level photoemission spectrum across the Mott transition, revealing how the spectral features and divergences depend on interaction strength and core-hole potential using advanced theoretical methods.

Contribution

It provides a detailed theoretical analysis of the photoemission spectrum across the Mott transition, highlighting the dependence of spectral singularities on interaction parameters and core-hole potential.

Findings

Asymmetric power-law divergence in metallic phase with exponent depending on U and Q

Vanishing of the divergence at the transition for certain Q values

Spectral peaks in insulator explained by molecular orbital approach

Abstract

The zero temperature core-level photoemission spectrum is studied across the metal to Mott insulator transition using dynamical mean-field theory and Wilson's numerical renormalization group. An asymmetric power-law divergence is obtained in the metallic phase with an exponent alpha(U,Q)-1 which depends on the strength of both the Hubbard interaction U and the core-hole potential Q. For Q <~ U_c/2 alpha decreases with increasing U and vanishes at the transition (U -> U_c) leading to a symmetric peak in the insulating phase. For Q >~ U_c/2, alpha remains finite close to the transition, but the integrated intensity of the power-law vanishes and there is no associated peak in the insulator. The weight and position of the remaining peaks in the spectra can be understood within a molecular orbital approach.