Seminar: Jose Lorenzana – University of Copenhagen

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Seminar: Jose Lorenzana

Title: Manipulating electronic states with light

I will review recent theory and experiments in which the electronic state of a material is controlled with light pulses. In the case of a superconductor[1], I will show that an impulsive stimulated Raman mechanism allows putting the superconductor in a nonequilibrium state in which the condensate oscillates in time, allowing to detect excitations which are coupled to it and which may be involved in the pairing. In the case of magnetite [2], which has a metal-insulator transition which, as first proposed by Verwey is attributed to charge ordering, I will show a Raman mechanism by which the disordered charges, above the ordering temperature, can transiently be induced to order opposing common expectations that a laser pulse should heat the material and promote disorder. Both cases illustrate the formidable flexibility of Raman processes as a tool for ultrafast manipulation of condensed matter.

[1] B.Mansart et al., Proc. Nat. Acad. Sci. 110, 4539 (2013)

[2] J. Lorenzana et al. The Europ. Phys. J. ST 222, 1223 (2013)

[2] S. Borroni et al., arXiv:1507.07193