Abstract:
The results of a study on ultrafast photo-induced phenomena in the intrinsic magnetic semiconductor EuO, using the two-color optical pump-probe technique, are presented. Experimental data demonstrate photo-induced magnetization precession in the temperature range below the Curie temperature, excited by circularly polarized light. Numerical estimates have been performed for two possible mechanisms of optical excitation of the magnetization precession, related to the optical orientation effect and the inverse Faraday effect. Based on theoretical modeling, it is shown that the optical orientation of spin through the electron transition $4f^75d^0\to 4f^65d^1$ is the triggering mechanism of the magnetization precession. Photoexcitation of EuO by light with photon energy greater than the band gap leads to the formation of magnetic polarons due to the strong exchange interaction of the $5d^1$ electron spin with the spins of 4$f$ electrons. The dynamics of magnetic polarons in the time range from a few picoseconds to microseconds has been revealed. At temperatures slightly above the Curie temperature, a record high value of the magnetic moment of polarons has been established.
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