Potential of Raman scattering in probing magnetic excitations and their coupling to lattice dynamics

TL;DR

This review highlights how Raman scattering can be used to probe magnetic excitations, such as magnons and fractionalized quasiparticles, in various magnetic materials, providing insights into their dynamics and interactions.

Contribution

It provides a comprehensive overview of Raman scattering's potential in studying magnetic quasiparticles, including background, data interpretation, and applications to specific materials.

Findings

Confirmed magnons in long-range ordered magnets

Detected fractionalized excitations in Kitaev spin liquids

Estimated magnetic exchange interactions from Raman data

Abstract

Raman scattering is an excellent method for simultaneously determining the dynamics of lattice, spin, and charge degrees of freedom. Furthermore, polarization selection rules in Raman scattering enable momentum-resolved quasiparticle dynamics. In this review, we highlight the potential of Raman scattering in probing magnetic quasiparticles or excitations in various magnetic materials. We demonstrate how temperature-dependent Raman scattering data can confirm the existence of magnons in long-range ordered magnets and fractionalized excitations in Kitaev spin liquid candidates. To make this review easily understandable to novices, we provide background information on magnons and fractionalized excitations, and explain how they become visible in the Raman scattering process. We also show how to estimate magnetic exchange interactions from the data. For both types of magnetic materials, we discuss the impact of spin-phonon coupling on the lineshape of the phonon modes. In terms of materials, we present magnetic Raman scattering data of antiferromagnetic Sr2IrO4 and La2CuO4, ferromagnetic CrI3 monolayers, and Kitaev spin liquid candidates {\alpha}-RuCl3 and \b{eta}-Li2IrO3. Overall, our review demonstrates the versatility of the Raman scattering technique in probing quasiparticles in magnetic quantum materials. The review aims to inform young experimental researchers about the potential of Raman scattering, thereby motivating them to use this technique in their research.