Raman Spectroscopic Investigation of Kitaev Quantum Spin Liquids

TL;DR

This review discusses how Raman spectroscopy can be used to investigate Kitaev quantum spin liquids, highlighting recent experimental and theoretical developments in understanding these topologically entangled states.

Contribution

It provides an updated literature survey on the application of Raman spectroscopy to study Kitaev quantum spin liquids, emphasizing recent experimental insights.

Findings

Raman spectroscopy effectively probes Kitaev spin liquid excitations.

Experimental results reveal non-Kitaev interactions in candidate materials.

The review summarizes progress in identifying signatures of topological states.

Abstract

Quantum spin liquids, a highly topologically entangled, dynamically correlated state where quantum fluctuations preclude any long-range ordering down to absolute zero. In the search for a topologically robust qubit, the scientific community has been in continuous hunt for real quantum spin liquid systems. Alexei Kitaev in his exactly solvable model for a spin-1/2 two-dimensional honeycomb lattice, presented a system that hosts a topologically protected state (Majorana zero-modes). Under an applied external field, the Kitaev spin liquids turn into a topologically non-trivial chiral spin-liquid state with non-abelian anionic excitations, which is crucial for quantum computing. Earlier theoretical predictions advocated that Kitaev physics can be realized in spin-orbit-coupled Mott insulators such as honeycomb irradiates and ruthenates. However, the experimental findings continuously challenge the theoretical aspects, indicating the presence of non-Kitaev interactions in real materials, where the dimensionality, disorder (vacancy), chemical composition, generalized spin-S, and external perturbations (pressure, magnetic field, temperature) can actively tune the Kitaev interactions and the ground state excitations. In this review article, a comprehensive discussion is included with an updated literature survey in the context of the potential of Raman spectroscopy as a probe for Kitaev quantum spin liquids.