Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 18: Critical Phenomena and Phase Transitions
DY 18.6: Vortrag
Montag, 12. März 2018, 16:45–17:00, BH-N 333
cooperative elastic self-amplification in molecular materials induced by ultrafast spin state photo-switching — •Roman Bertoni1, Marco Cammarata1, Hervé Cailleau1, Maciej Lorenc1, Eric Collet1, and Cristian Enaschescu2 — 1University Rennes 1, UMR UR1-CNRS 6251, Rennes, France — 2Faculty of Physics, Alexandru Ioan Cuza University, Iasi, Romania
The field of Photo-Induced Phase transition (PIPT) is reaching dynamical material control at fundamental time scale. Amongst molecular photo-switchable materials, spin crossover crystals are archetype of molecular bi-stability. We are now able to switch and control such systems at ultrafast time scale. The ultrafast photo-switching of these materials leads to a complex multistep out-of-equilibrium dynamics spanning from local molecular process to macroscopic material changes. The initial photo-switching process occurs within one picosecond at the local molecular scale involving coherent structural dynamics [1]. At longer time scale, the material response departs from that observed in diluted molecules due to the lattice action through structural feedback. Our new results have evidenced the existence of self-amplified elastic amplification during the volume expansion of the material inducing a multiplication of the fraction of molecules by factor five [3]. Such elastically-driven cooperativity triggered by a light pulse offers a new efficient way to generate and stabilize photo-induced phases in many volume-changing materials. [1]M. Cammarata et al, Phys. Rev. Lett 113, 227402 (2014)[2]R. Bertoni et al, Nature Materials 15 606-610 (2016)