Description
We develop a Floquet theory tailored for resonant inelastic X-ray scattering (RIXS) and present first results employing our formalism. In particular, there are two effects of a periodic driving: (i) the dipolar light-matter transition can be interpreted as a non-local operator, (ii) elastic-like resonances and orbital excitations in the RIXS signal show different selection rules on the Floquet side-bands.
Second, we investigate signatures of dynamical screening on charge-transfer insulators in X-ray absorption spectroscopy (XAS). One can observe a redshift of the excitonic main peak, as also seen in experiments [1,2], interpreted as Hubbard-band renormalization, and additional screening mode excitations. Their presence and amplitude depends on the nature of the screening (adiabatic to anti-adiabatic) and the lifetime of the final core-hole after absorption. We discuss these phenomena in the case of damped and undamped screening; latter is computed with a new, efficient impurity solver employing a complex-mode decomposition of the hybridization function (the screening propagator).
References
[1] Lojewski et al., Photo-induced charge-transfer renormalization in NiO, arXiv:2305.10145v2
[2] Baykusheva et al., Ultrafast Renormalization of the On-Site Coulomb Repulsion in a Cuprate Superconductor, PRX 12, 011013
