Detecting Crystallographic Lattice Chirality using Resonant Inelastic X-ray Scattering

TL;DR

This paper demonstrates theoretically that resonant inelastic X-ray scattering (RIXS) can be used to distinguish the chirality of crystal lattices, providing a new method for detecting crystallographic handedness in magnetic materials.

Contribution

The study introduces a theoretical framework showing RIXS spectrum sensitivity to lattice chirality and proposes a Flack parameter for chiral identification in magnetic systems.

Findings

RIXS spectrum varies with lattice handedness in RbFeSe.

Inter- and intra-band magnon scattering peaks are sensitive to chirality.

A Flack parameter based on RIXS response effectively distinguishes chiral orientations.

Abstract

The control and detection of crystallographic chirality is an important and challenging scientific problem. Chirality has wide ranging implications from medical physics to cosmology including an intimate but subtle connection in magnetic systems, for example Mn$_{1-x}$Fe$_{x}$Si. X-ray diffraction techniques with resonant or polarized variations of the experimental setup are currently utilized to characterize lattice chirality. We demonstrate using theoretical calculations the feasibility of indirect $K$ -edge bimagnon resonant inelastic X-ray scattering (RIXS) spectrum as a viable experimental technique to distinguish crystallographic handedness. We apply spin wave theory to the recently discovered $\sqrt {5}\times\sqrt {5}$ vacancy ordered chalcogenide Rb$_{0.89}$Fe$_{1.58}$Se$_{2}$ for realistic X-ray experimental set up parameters (incoming energy, polarization, and Bragg angle) to show that the computed RIXS spectrum is sensitive to the underlying handedness (right or left) of the lattice. A Flack parameter definition that incorporates the right- and left- chiral lattice RIXS response is introduced. It is shown that the RIXS response of the multiband magnon system RbFeSe arises both from inter- and intra- band scattering processes. The extinction or survival of these RIXS peaks are sensitive to the underlying chiral lattice orientation. This in turn allows for the identification of the two chiral lattice orientations.