Phase ordering of charge density waves traced by ultrafast low-energy electron diffraction

By S. Vogelgesang, G. Storeck, J. Horstmann, T. Diekmann, M. Sivis, S. Schramm, K. Rossnagel, Sascha Schäfer, C. Ropers. Nature Physics, 2017

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We introduce ultrafast low-energy electron diffraction (ULEED) in backscattering for the study of structural dynamics at surfaces. Using a tip-based source of ultrashort electron pulses, we investigate the optically driven transition between charge density wave phases at the surface of 1T-TaS2. The large transfer width of the instrument allows us to employ spot-profile analysis, resolving the phase-ordering kinetics in the nascent incommensurate charge density wave phase. We observe a coarsening that follows a power-law scaling of the correlation length, driven by the annihilation of dislocation-type topological defects of the charge-ordered lattice. Our work opens up the study of a wide class of structural transitions and ordering phenomena at surfaces and in low-dimensional systems. A tracing of the phase-ordering kinetics of a charge density wave system demonstrates the potential of ultrafast low-energy electron diffraction for studying phase transitions and ordering phenomena at surfaces and in low-dimensional systems.

Subfields: Atomic and Molecular Physics, and Optics, Geophysics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/0e8dedc0cc0da6dc4d0044a110df83b242dc0ce6