University
of California, Davis
Physics
Department
Condensed
Matter Seminar
"Femtosecond X-ray
Diffraction and Spectroscopy: new Light on the Dynamics of Phase Transitions in
Strongly Correlated Systems"
In
this talk I will discuss novel time-resolved x-ray spectroscopies of condensed
matter, aimed at providing critical insight into the relationship between
atomic, electronic and magnetic structures of a solid. By combining visible/IR
excitation with ultrafast x-ray probing, we can measure the structural
properties of the system along the elementary, non-equilibrium physical pathway
of a phase transition. This goes well beyond traditional spectroscopic
techniques, which rely on adiabatic tuning of external parameters across
critical points. Specific phenomena of interest include the ultrafast response
of transition metal oxides to impulsive photo-doping of holes in particular
valence shells or to coherent excitation of IR-active vibrations. I will
discuss a study of the photo-induced insulator-to-metal transition in
non-magnetic VO2, where the respective role of structural and electronic
degrees of freedom is critically evaluated. Ongoing work on the ultrafast
physics and photo-induced dynamics in CMR compounds will also be discussed.
4:10p.m., 416 Phy/Geo