Abstract
We present a study of photoexcited magnetization dynamics in ferromagnetic (Ga,Mn)As films observed by time-resolved magneto-optical measurements. The magnetization precession triggered by linearly polarized optical pulses in the absence of an external field shows a strong dependence on photon frequency when the photoexcitation energy approaches the band edge of (Ga,Mn)As. This can be understood in terms of magnetic anisotropy modulation by both laser heating of the sample and by hole-induced nonthermal paths. Our findings provide a means for identifying the transition of laser-triggered magnetization dynamics from thermal to nonthermal mechanisms, a result that is of importance for ultrafast optical spin manipulation in ferromagnetic materials via nonthermal paths.
2 More- Received 28 December 2014
- Revised 27 March 2015
DOI:https://doi.org/10.1103/PhysRevB.91.195204
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