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 . After this initial relaxation, one obtains a photo-doped
state, in which both the electronic spectra and the exchange interactions  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 . In the regime of strong driving, even the sign of the
exchange interaction can be reversed from an antiferromagnetic to a ferromagnetic coupling.
 M. Eckstein and Ph. Werner, Sci. Rep 6, 21235 (2016)
 J.H. Mentink and M. Eckstein, Phys. Rev. Lett. 113, 057201 (2014).
 J.H. Mentink, K. Balzer, and M. Eckstein, Nature Comm. 6, 6708 (2015).