Visualizing the melting of periodic lattice distortions in a complex 2D charge density wave material via MeV-scale ultrafast electron diffraction

We discuss our experiments that apply ultrafast electron diffraction (UED) to study structural dynamics of the phase transition in single crystal tantalum ditelluride, TaTe2, a quasi-2D quantum material which exhibits a trimer superstructure at cryogenic temperatures. Intense near-infrared (NIR) pulses at 1030 nm are employed to quench the low temperature, atomically ordered state and the process is captured by ultrashort bunches of electrons as a function of pump-probe time delay. The diffraction signatures of the trimer superstructure recover on picosecond time scales. These measurements of TaTe2 underscore moreover the applicability of the HiRES UED beamline at Lawrence Berkeley National Laboratory (LBNL) to probe ultrafast structural dynamics of complex materials.