Polarized Raman Response of Two-Dimensional Quasiperiodic Antiferromagnets: Configuration-Interaction versus Green's Function Approaches

TL;DR

This paper investigates the Raman response of quasiperiodic antiferromagnets using both Green's function and configuration-interaction methods, revealing new symmetry modes and the significant role of multimagnon fluctuations in Raman intensity.

Contribution

It introduces a comparative analysis of Green's function and configuration-interaction approaches for calculating Raman responses in quasiperiodic antiferromagnets, highlighting the advantages of the configuration-interaction scheme.

Findings

Identification of a single Raman-active mode under Loudon-Fleury mechanism.

Activation of additional symmetry modes via dynamic ring exchange and chiral fluctuations.

Major contribution of multimagnon fluctuations to Raman intensity.

Abstract

We study Raman response of Heisenberg antiferromagnets on the $\mathbf{C}_\mathrm{5v}$ Penrose and $\mathbf{C}_\mathrm{8v}$ Ammann-Beenker lattices within and beyond the Loudon-Fleury second-order perturbation scheme intending to explore optical features peculiar to quasiperiodic magnets. Within the Loudon-Fleury mechanism, we find one and only Raman-active mode of $\mathrm{E}_2$ symmetry without any dependence on linear incident and scattered polarizations. Beyond the Loudon-Fleury mechanism, two more symmetry species $\mathrm{A}_1$ and $\mathrm{A}_2$ are activated via dynamic ring exchange and chiral spin fluctuations, respectively, which can be extracted by the use of circular as well as linear polarizations. We employ Green's functions on one hand and configuration-interaction wavefunctions on the other hand to calculate the multimagnon contributions to inelastic light scatterings. Demonstrating the great advantage of the configuration-interaction scheme, we reveal that a major portion of the Shastry-Shraiman fourth-order Raman intensity is mediated by multimagnon fluctuations.