Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 68: Focus Session: Non-equilibrium Dynamics in Light-driven Materials: Theory Meets Experiment

O 68.2: Hauptvortrag

Mittwoch, 22. März 2017, 11:00–11:30, TRE Phy

Pump/probe photoemission spectroscopy in charge density wave insulators — •James Freericks — Department of Physics, Georgetown University, Washington, DC 20057

In this talk, I will discuss time-resolved photoemission spectroscopy in charge-density-wave (CDW) insulators that form due to an electronic nesting instability. A strongly correlated electronic CDW has a number of interesting features. As the temperature is raised, the gap in the spectrum remains unchanged all the way up to Tc, while the gap fills with subgap states, which eventually metallize the system. There is a critical interaction strength where the metallization occurs the instant the temperature is increased from 0. The system also displays Mott-like physics at strong interaction strength. We illustrate that these systems have an interesting response to the pump. In some cases, the gap region fills in due to the pump, implying the disappearance of the spectral gap, but in the presence of a well formed spatial charge-density-wave order parameter. At the critical interaction strength, the system is exceedingly difficult to pump. Whatever energy is pumped in on the leading edge of the electric field, is pumped out on the trailing edge. These calculations result from the exact solution of the nonequilibrium Falicov-Kimball model via dynamical mean-field theory. We also discuss experimental implications for these results.