Femtosecond time-resolved X-ray diffraction is used to study a photo-induced phase transition between two charge density wave (CDW) states in 1T-TaS2, namely the nearly commensurate (NC) and the incommensurate (I) CDW states. Structural modulations associated with the NC-CDW order are found to disappear within 400 fs. The photo-induced I-CDW phase then develops through a nucleation/growth process which ends 100 ps after laser excitation. We demonstrate that the newly formed I-CDW phase is fragmented into several nanometric domains that are growing through a coarsening process. The coarsening dynamics is found to follow the universal Lifshitz-Allen-Cahn growth law, which describes the ordering kinetics in systems exhibiting a non-conservative order parameter.
@article{arxiv.1703.07465,
title = {Watching the birth of a charge density wave order: diffraction study on nanometer-and picosecond-scales},
author = {C. Laulhé and T. Huber and G. Lantz and A. Ferrer and S. O. Mariager and S. Grübel and J. Rittmann and J. A. Johnson and V. Esposito and A. Lübcke and L. Huber and M. Kubli and M. Savoini and V. L. R. Jacques and L. Cario and B. Corraze and E. Janod and G. Ingold and P. Beaud and S. L. Johnson and S. Ravy},
journal= {arXiv preprint arXiv:1703.07465},
year = {2017}
}