Condensed Matter Seminar: Local ultrafast dynamics of order parameters captured by ultrafast X-ray and electron nanoscopy

"Transient states of matter emerging from intense optical driving have attracted much interest recently, presenting properties such as light-induced superconductivity and band topology. However, the observables of such short-lived physical settings are exclusively limited to those accessible by ultrashort probes. This talk discusses state-of-the-art nanoscopic spectroscopies of dynamics at the scale of a few femtoseconds to a few picoseconds using two short-wavelength probes: coherent soft-X-ray scattering and ultrafast electron microscopy (1 ps =1000 fs = 10^-12 sec). The first part presents an experimental effort to quantify the speed of hot electrons (v_e) as they cross an order-parameter domain-wall in a thin magnetic multilayer sample. The second part presents experiments on an ultrafast transmission electron microscope (UTEM) in Göttingen, Germany. Among other examples, I will show how ultrafast electron microscopy of 1T-TaS2 observes the melting and revival dynamics of the nearly-commensurate CDW/PLD phase (charge density wave and periodic lattice distortions). Finally, I will present the pulsed microscopes that arrive soon at TAU."