Séminaire du LPTMS: Serguei Brazovskii ***séminaire exceptionnel ***


14:30 - 15:30

LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay
15 Rue Georges Clemenceau, Orsay, 91405

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Modeling of dynamical phase transitions in electronic systems induced by ultra-fast optical pumping

Serguei Brazovskii (LPTMS)

I shall report the recent studies on phenomenological theory of dynamical phase transformations in cooperative electronic systems achieved by means of a femto-second optical pumping.
1. Experiments on charge density waves recovered coherent unharmonic undulations of the order parameter, critical slowing down of the collective mode, and evolution of the particles spectra. The numerical modeling reproduced the dynamical phase transition, and the waves emitted by “earthquakes” from in depth annihilation events of domain walls.
2. The special case of resonance optical pumping to excitons is realized in systems with a neutral-ionic ferroelectric transition. The modeling of the quantum-coherent quasi-condensate of excitons interacting with the order parameter recovers the dynamical realization of the “excitonic insulator” state and spacio-temporal patterns with self-focusing, domains segregation, and local dynamical phase transitions.

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