Combining the temporal resolution of optical spectroscopy with the spatial resolution of electron microscopy, ultrafast transmission electron microscopy (UTEM) enables resolving out-of-equilibrium processes in heterogeneous systems on the sub-nanometer length scale using imaging, diffraction and spectroscopy [1]. Here, we employ the Göttingen UTEM [2] to unravel real-space dynamics of an order parameter to a charge-density wave (CDW) phase transition in the correlated material 1T-TaS2. Specifically, a tailored dark-field approach enables tracking of dynamics of the CDW amplitude with nanometer spatial resolution. Following a global CDW quench, we observe localized formation, condensation and subsequent spatiotemporal evolution of domain patterns on femtosecond to nanosecond time scales. We corroborate our findings by time-dependent Ginzburg-Landau simulations. [1] A. H. Zewail, Science 328, 187 (2010). [2] A. Feist et al., Ultramicroscopy 176, 63 (2017).
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