Speckle patterns manifesting from the interaction of coherent X-rays with matter offer a glimpse into the dynamics of nanoscale domains that underpin many emergent phenomena in quantum materials. While the dynamics of the average structure can be followed with time-resolved X-ray diffraction, the ultrafast evolution of local structures in nonequilibrium conditions have thus far eluded detection due to experimental limitations, such as insufficient X-ray coherent flux. Here we demonstrate a nonequilibrium speckle visibility experiment using a split-and-delay setup at an X-ray free-electron laser. Photoinduced electronic domain fluctuations of the magnetic model material Fe3O4 reveal changes of the trimeron network configuration due to charge dynamics that exhibit liquid-like fluctuations, analogous to a supercooled liquid phase. This suggests that ultrafast dynamics of electronic heterogeneities under optical stimuli are fundamentally different from thermally-driven ones.
@article{arxiv.2408.10050,
title = {Imaging ultrafast electronic domain fluctuations with X-ray speckle visibility},
author = {N. Hua and Y. Sun and P. Rao and N. Zhou Hagström and B. K. Stoychev and E. S. Lamb and M. Madhavi and S. T. Botu and S. Jeppson and M. Clémence and A. G. McConnell and S. -W. Huang and S. Zerdane and R. Mankowsky and H. T. Lemke and M. Sander and V. Esposito and P. Kramer and D. Zhu and T. Sato and S. Song and E. E. Fullerton and O. G. Shpyrko and R. Kukreja and S. Gerber},
journal= {arXiv preprint arXiv:2408.10050},
year = {2024}
}