Faculté des sciences

Transient spin density wave order induced in the normal state of BaFe 2 As 2 by coherent lattice oscillations

Kim, Kyung Wan ; Pashkin, A. ; Schäfer, H. ; Beyer, M. ; Porer, M. ; Wolf, T. ; Bernhard, Christian ; Demsar, J. ; Huber, R. ; Leitenstorfer, A.

In: EPJ Web of Conferences, 2013, vol. 41, p. 03012

We trace the ultrafast dynamics of the spin density wave gap of the pnictide system BaFe2As2 probing resonantly with broadband multi-terahertz pulses. The photoexcitation in the low-temperature ground state leads to a fast suppression of the spin order followed by a slower recovery process. Surprisingly, in the normal state, we observe periodic oscillations of the spin density wave feature at a... Plus

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    Summary
    We trace the ultrafast dynamics of the spin density wave gap of the pnictide system BaFe2As2 probing resonantly with broadband multi-terahertz pulses. The photoexcitation in the low-temperature ground state leads to a fast suppression of the spin order followed by a slower recovery process. Surprisingly, in the normal state, we observe periodic oscillations of the spin density wave feature at a frequency as high as 5.5 THz. Our results indicate a transient development of a macroscopic order driven by a coherent lattice oscillation and attest to a pronounced spin–phonon coupling in pnictides.