Seminars Archive

Ultrafast dynamics of short-range magnetic correlations in a spin-chain cuprate

Abstract
Resonant inelastic x-ray scattering (RIXS) is a powerful x-ray spectroscopy that is sensitive to all degrees of freedom of condensed matter. With the development of x-ray free electron lasers (XFEL), it becomes now possible to perform time-resolved RIXS to access their time-domain dynamics. Here I will first present static RIXS data obtained at O K-edge on the quasi-one-dimensional spin-chains CuGeO3 at the ADRESS beamline at Swiss Light Source. In this edge-sharing chain cuprate having a standard Cu d9 electronic configuration, RIXS can create a particular excitation called a Zhang-Rice singlet (ZRS) in its final state. The ZRS consists in a double-hole occupation on a CuO4 plaquette, which occurs via an effective hole transfer from one plaquette to another. The intensity of this excitation depends on the ground state spin configuration and is a measure of the nearest-neighbour spin arrangement. This effect is used here to monitor the intrachain short-range spin correlations in CuGeO3 as a function of temperature [1]. I will also present recent time-resolved RIXS data obtained at the SXR beamline of the XFEL LCLS. After photoexciting CuGeO3 with 266 nm photon pulses, we observe a transient suppression of the ZRS intensity within a few picoseconds. Its recovery is then tracked over hundreds of picoseconds. This allows us to monitor the ultrafast dynamics of short-range spin correlations CuGeO3. [1] C. Monney et al., PRL 110, 087403 (2013)