F. Liu, T. Makino, T. Yamazaki, K. Ueno, A. Tsukazaki, T. Fukumura, Y. Kong, M. Kawasaki
We have investigated the ultrafast spin dynamics in EuO thin films by time-resolved Faraday rotation spectroscopy. The photo-induced magnetization is found to be increased in a transient manner, accompanied with subsequent demagnetization. The dynamical magnetization enhancement showed a maximum slightly below the Curie temperature with prolonged tails toward both lower and higher temperatures and dominates the demagnetization counterpart at 55 K. The magnetization enhancement component decays in ~1 ns. The realization of the transient collective ordering is attributable to the enhancement of the f-d exchange interaction due to the formation of the magnetic polaron.
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http://arxiv.org/abs/1205.2818
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