Electronic Raman scattering in correlated materials: exact treatment of nonresonant, mixed, and resonant scattering with dynamical mean field theory

TL;DR

This paper presents an exact dynamical mean field theory solution for electronic Raman scattering in correlated materials, analyzing nonresonant, mixed, and resonant responses, especially near a Mott-Hubbard transition.

Contribution

It extends previous models to include resonant effects and provides an exact treatment for the Falicov-Kimball model within DMFT, highlighting resonance phenomena in Raman scattering.

Findings

Resonant effects significantly enhance Raman features near double resonance.

Joint resonance occurs when incident photon energy matches interaction strength.

Resonance effects exhibit isosbestic behavior across different symmetry sectors.

Abstract

We solve for the electronic Raman scattering response functions on an infinite-dimensional hypercubic lattice employing dynamical mean field theory. This contribution extends previous work on the nonresonant response to include the mixed and resonant contributions. We focus our attention on the spinless Falicov-Kimball model, where the problem can be solved exactly, and the system can be tuned to go through a Mott-Hubbard-like metal-insulator transition. Resonant effects vary in different scattering geometries, corresponding to the symmetries of the charge excitations scattered by the light. We do find that the Raman response is large near the double resonance, where the transfered frequency is close to the incident photon frequency. We also find a joint resonance of both the charge-transfer peak and the low-energy peak when the incident photon frequency is on the order of the interaction strength. In general, the resonance effects can create order of magnitude (or more) enhancements of features in the nonresonant response, especially when the incident photon frequency is somewhat larger than the frequency of the nonresonant feature. Finally, we find that the resonant effects also exhibit isosbestic behavior, even in the A1g and B2g sectors, and it is most prominent when the incident photon frequency is on the order of the interaction energy.