SFB 668


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24.5.2016, 17:00
Jungiusstr. 11, Hörsaal AP

SFB 668 - Seminar

Prof. Dr. M. Eckstein (CFEL, Hamburg):

Dynamics of antiferromagnetic states on the femtosecond timescale

Femtosecond laser technology has opened the possibility to probe and control the dynamics of condensed matter phases on microscopic timescales. In this talk I discuss recent efforts to theoretically describe the dynamics of antiferromagnetic states under photoexcitation. We show that photo-induced carriers can pass their energy to antiferromagnetic spin correlations on the ultra-short timescale of 20fs [1]. After this initial relaxation, one obtains a photo-doped state, in which both the electronic spectra and the exchange interactions [2] differ from the equilibrium properties. This shows that photo-doping can be used to efficiently modify the magnetic magnetic order in an ultrafast way. Furthermore, we also demonstrate the possibility of a reversible modification of magnetic exchange interactions while the system is under the influence of the laser field [3]. In the regime of strong driving, even the sign of the exchange interaction can be reversed from an antiferromagnetic to a ferromagnetic coupling. [1] M. Eckstein and Ph. Werner, Sci. Rep 6, 21235 (2016) [2] J.H. Mentink and M. Eckstein, Phys. Rev. Lett. 113, 057201 (2014). [3] J.H. Mentink, K. Balzer, and M. Eckstein, Nature Comm. 6, 6708 (2015).

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