Resonant two-magnon Raman scattering in antiferromagnetic insulators

TL;DR

This paper develops a theory for resonant two-magnon Raman scattering in antiferromagnetic insulators, revealing how it provides insights into magnetism and doping effects, and explaining experimental anomalies near electronic band gaps.

Contribution

It introduces a new theoretical framework for resonant Raman scattering that accounts for the dominant diagrams and explains experimental features in antiferromagnetic insulators.

Findings

Identifies the dominant diagram for resonant Raman intensity.

Explains the frequency dependence of the two-magnon peak.

Accounts for unusual two-magnon spectral features near the band gap.

Abstract

We propose a theory of two-magnon {\it resonant\/} Raman scattering from antiferromagnetic insulators, which contains information both on the magnetism and the carrier properties in the lighly doped phases. We argue that the conventional theory does not work in the resonant regime, in which the energy of the incident photon is close to the gap between the conduction and valence bands. We identify the diagram which gives the dominant contribution to Raman intensity in this regime and show that it can explain the unusual features in the two-magnon profile and in the two-magnon peak intensity dependence on the incoming photon frequency.