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arXiv · 0706.4270

Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation

J. Qi·Y. Xu·N. Tolk·X. Liu·J. K. Furdyna·I. E. Perakis
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Abstract

We use femtosecond optical pulses to induce, control and monitor magnetization precession in ferromagnetic Ga0.965Mn0.035As. At temperatures below ~40 K we observe coherent oscillations of the local Mn spins, triggered by an ultrafast photoinduced reorientation of the in-plane easy axis. The amplitude saturation of the oscillations above a certain pump intensity indicates that the easy axis remains unchanged above ~TC/2. We find that the observed magnetization precession damping (Gilbert damping) is strongly dependent on pump laser intensity, but largely independent on ambient temperature. We provide a physical interpretation of the observed light-induced collective Mn-spin relaxation and precession.

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J. Qi, Y. Xu, N. Tolk, X. Liu, J. K. Furdyna, I. E. Perakis. 2007-07-19. Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation. https://doi.org/10.1063/1.2785114

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