Resonant inelastic X-ray scattering (RIXS) has become a powerful spectroscopic technique for investigating elementary excitations in quantum materials [1, 2]. In particular, soft X-ray RIXS provides element-specific access to electronic, magnetic, and lattice excitations, including crystal-field (dd) excitations, magnons, paramagnons, and phonons.
In this seminar, I will briefly introduce the basic principles of soft X-ray RIXS and its experimental capabilities, including the instrumentation at the TPS 41A beamline of the Taiwan Photon Source [3]. I will then present selected RIXS studies of correlated electron systems conducted at NSRRC. Finally, I will discuss our recent research on circular dichroism in RIXS and chiral phonons in magnetic materials, with particular emphasis on the interplay between magnetic order, lattice dynamics, and emerging concepts in altermagnetism [4]. These studies illustrate how polarization-dependent RIXS can provide new insights into the coupling between electronic, magnetic, and lattice degrees of freedom.
References
[1]: L. J. P. Ament et al., Rev. Mod. Phys. 83, 705 (2011).
[2]: M. Mitrano et al., Phys. Rev. X 14, 040501 (2024).
[3]: A. Singh et al., J. Synchrotron Rad. 28, 977 (2021).
[4]: J. Okamoto et al., arXiv: 2512.00388 (2025).