“Dynamical investigation of ordering phase transitions: from soft matter to strongly correlated systems” by Fabrizio Carbone (EPFL Lausanne)

Wednesday, January 18, 2017 - 4:00pm
Condensed Matter Physics Journal Club

In collective systems, the equilibrium between long-range and short-ranges forces decides the spatial distribution of the individual constituents and its ordering properties. 

Examples can be found in soft-matter where self-assembly can lead to the formation of supra-crystals and quasi-ordered aggregates, or in condensed matter systems where charges or spins can order to form textured insulating or metallic states with intriguing electronic or magnetic properties.

In this seminar, we will show that microscopic insights in the mechanisms behind ordering phase transitions in such systems can be gained by combining time-resolved electron diffraction and optical spectroscopy.

In particular, we will show few examples of this phenomenology in the context of self-assembled supra crystals, metal-insulator and metal-superconductor phase transitions.

Recently, we found that the ligands in a self-assembled supra-crystal of functionalized gold NanoParticles (NP) can be transiently annealed into a quasi-ordered state by fs light pulses.

In another example, combining fs-optics and electron diffraction, new microscopic details on the Verwey transition in magnetite were revealed, suggesting a route for the coherent control of the charge-ordered phase by light pulses.

Finally, In cuprates superconductors, the coherent oscillations of the Cooper pairs condensate as well as coherent structural vibrations were detected via the Impulsive Stimulated Raman Scattering (ISRS) mechanism. In this framework, the coupling between low-energy collective modes and high-energy electronic excitations was addressed in a quantitative fashion combining theoretical calculations with our experimental findings.

PAB 4-330