Theory of two magnon Raman scattering in antiferromagnetic iron pnictides

TL;DR

This paper develops a theoretical framework for understanding two-magnon Raman scattering in antiferromagnetic iron pnictides, revealing how different spin models influence the scattering response and suggesting low magnetic frustration in these materials.

Contribution

It introduces a local moment perspective to analyze two-magnon Raman scattering across various quantum spin models for iron pnictides, highlighting the impact of magnetic frustration.

Findings

Two-magnon Raman response varies significantly with magnetic frustration.

Raman scattering can serve as an independent probe of spin interactions.

Results suggest low magnetic frustration in iron pnictides.

Abstract

Although the parent iron-based pnictides and chalcogenides are itinerant antiferromagnets, the use of local moment picture to understand their magnetic properties is still widespread. We study magnetic Raman scattering from a local moment perspective for various quantum spin models proposed for this new class of superconductors. These models vary greatly in the level of magnetic frustration and show a vastly different two-magnon Raman response. Light scattering by two-magnon excitations thus provides a robust and independent measure of the underlying spin interactions. In accord with other recent experiments, our results indicate that the amount of magnetic frustration in these systems may be small.