Electronic and Structural Dynamics in Solids: A Momentum-Resolved View on Microscopic Coupling and Correlation Phenomena
14:00 - 15:00
Max Planck Research Group for Structural & Electronic Surface Dynamics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
CFEL (Bldg. 99)
Seminar Room I-III, EG.076-080
The coupling and mutual dependence of electronic and vibrational degrees of freedom is at the heart of microscopic as well as macroscopic phenomena in condensed matter. Ultrafast pump-probe techniques provide experimental access to these coupling and correlation effects by revealing the response of electrons and lattice to specific excitation of a material.
We employ a set of complementary techniques: i) time- and angle-resolved
photoelectron spectroscopy (trARPES) based on a 0.5 MHz laser 
generating XUV pulses provides access to the spectral function and the
dynamics of excited states throughout the Brillouin zone; ii)
femtosecond electron diffraction (FED)  and optical spectroscopy are
used to study phonon dynamics  and phase transitions ; and iii)
electron point-projection microscopy allows for imaging of ultrafast
carrier transport in nanostructures .
In particular, I will
discuss electron and phonon dynamics in the semiconducting transition
metal dichalcogenide WSe2. We demonstrate mapping of the conduction band and the generation of spin- and pseudospin-polarized excited states in
this centrosymmetric material . A momentum-resolved view of the
phonon dynamics is obtained from by FED.
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 M. Müller et al., Nature Communications 5, 5292 (2014); M. Müller et al., ACS Photonics 3, 611 (2016).
 R. Bertoni et al., arXiv:1606.03218.