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Strong correlations between spin, charge and orbital degrees of freedom play an important role in materials and a recent development of ultrafast spectroscopies enabled to disentangle these relevant degrees of freedom by their temporal evolution. I will start with a summary of the charge carrier relaxation after the photo-excitation in Mott insulators described within the dynamical mean field theory (DMFT) and continue how this formalism can be extended to including the role of dynamical screening and non-local fluctuations (GW+EDFMT)[1,2]. Then I will open the question how to use the laser pulse to manipulate screening in Mott insulators. As an extreme example I will present a self-trapping of the system in the negative temperature state by a proper manipulation of the screening environment, which leads to the enhanced subgap response in the charge susceptibility. This population inversion leads to the low-energy anti-screening and I will comment on its experimental relevance. In the second part I will shed light on the role of spin fluctuations in the relaxation dynamics, which can be analysed by an extension of DMFT[3]. I will exemplify how optical pump probe techniques can be used to detect some basic theoretical ideas in higher dimensional doped antiferromagnets, like string states, Trugman paths and the lack of spin-charge separation. At the end I will provide an outlook how to extend these tools to an ab-initio description of strongly correlated materials out of equilibrium. [1] D. Golez, M. Eckstein, and P. Werner. Phys. Rev. B, 92:195123, Nov (2015). [2] D. Golez, L. Boehnke, H. U. R. Strand, M. Eckstein, and P. Werner. Phys. Rev. Lett. 118:246402 (2017). [3] N. Bittner, D. Golez, M. Eckstein, P. Werner, in preparation.

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Denis Golez, University of Fribourg
Seminar Room 0.03, ETP
Contact: Zala Lenarcic