Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation

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.

7 pages,3 figures

References in corpus (6)

• Hole-mediated ferromagnetism in tetrahedrally coordinated semiconductors
• Theory of ferromagnetic (III,Mn)V semiconductors
• Temperature-dependent magnetization in diluted magnetic semiconductors
• Magnetization relaxation in (Ga,Mn)As ferromagnetic semiconductors
• Mean-field magnetization relaxation in conducting ferromagnets
• Ultrafast light-induced magnetization dynamics in ferromagnetic semiconductors

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• Magnetization Relaxation and Collective Spin Excitations in Correlated Double--Exchange Ferromagnets
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• Theory of atomistic simulation of spin-transfer torque in nanomagnets
• Collective magnetization dynamics in ferromagnetic (Ga,Mn)As mediated by photo-excited carriers
• Establishing micromagnetic parameters of ferromagnetic semiconductor (Ga,Mn)As