Indirect K-edge bimagnon resonant inelastic X-ray scattering spectrum of $\alpha$-FeTe

TL;DR

This paper calculates the K-edge bimagnon RIXS spectra of $ ext{FeTe}$'s bicollinear antiferromagnetic order, revealing multiple excitation channels and spectral features that differ from other magnetic orders, aiding understanding of spin excitations.

Contribution

The study provides the first detailed calculation of bimagnon RIXS spectra for bicollinear antiferromagnetic order in $ ext{FeTe}$, highlighting unique spectral features and their dependence on magnetic interactions.

Findings

RIXS spectra can show 1-3 peaks depending on energy-momentum conditions.

Spectrum does not vanish at the magnetic ordering wave vector $(rac{ ext{pi}}{2},-rac{ ext{pi}}{2})$.

Spectral features are sensitive to next-next nearest neighbor and biquadratic interactions.

Abstract

We calculate the K-edge indirect bimagnon resonant inelastic X-ray scattering (RIXS) intensity spectra of the bicollinear antiferromagnetic order known to occur in the $\alpha$-FeTe chalcogenide system. Utilizing linear spin wave theory for this large-S spin system we find that the bimagnon spectrum contains four scattering channels (two intraband and two interband). We find from our calculations that for suitable energy-momentum combination the RIXS spectra can exhibit a one-, two- or three- peak structure. The number of peaks provides a clue on the various bimagnon excitation processes that can be supported both in and within the acoustic and optical magnon branches of the bicollinear antiferromagnet. Unlike the RIXS response of the antiferromagnetic or the collinear antiferromagnetic spin ordering, the RIXS intensity spectrum of the bicollinear antiferromagnet does not vanish at the magnetic ordering wave vector $(\pi/2,-\pi/2)$. It is also sensitive to next-next nearest neighbor and biquadratic coupling interactions. Our predicted RIXS spectrum can be utilized to understand the role of multi-channel bimagnon spin excitations present in the $\alpha$-FeTe chalcogenide.