Abstract
It was shown recently that the Fe magnetization reversal in the Fe/MnAs/GaAs(001) epitaxial system, attained by temperature control of the regular stripe pattern of the MnAs α- and β-phases, can also be driven by an ultrashort optical laser pulse. In the present time-resolved scattering experiment, we address the dynamics of the MnAs α-β self-organized stripe pattern induced by a 100 fs optical laser pulse, using as a probe the XUV radiation from the FERMI free-electron laser. We observe a loss in the diffraction intensity from the ordered α-β stripes that occurs at two characteristic timescales in the range of ~10−12 and ~10−10 s. We associate the first intensity drop with ultrafast electron-lattice energy exchange processes within the laser-MnAs interaction volume and the second with thermal diffusion towards the MnAs/GaAs interface. With the support of model calculations, the observed dynamics are interpreted in terms of the formation of a laterally homogeneous MnAs overlayer, the thickness of which evolves in time, correlating the MnAs microstructure dynamics with the Fe magnetization response.
Highlights
MnAs/GaAs(001) is a metal/semiconductor system in which the interplay between epitaxial constraints and temperature-driven phase transitions gives rise to a peculiar morphological and magnetic behavior [1]
The results of the optical-laser-pump–XUV-free-electron laser (FEL)-probe scattering experiments performed on the Fe/MnAs/GaAs(001) system at the FERMI FEL facility have revealed how the laser induced microstructure dynamics correlate with the observed Fe magnetization reversal
We monitored the temporal evolution of the ordered α/β-MnAs stripes after a short laser pulse of variable intensity by measuring complete rocking curves, which allowed us to separate specular reflectivity contributions from the 1st and 2nd order Bragg peaks originating from the ordered stripes
Summary
MnAs/GaAs(001) is a metal/semiconductor system in which the interplay between epitaxial constraints and temperature-driven phase transitions gives rise to a peculiar morphological and magnetic behavior [1]. Taking advantage of the element selectivity of resonant x-ray magnetic scattering experiments, it was demonstrated that the direction of the Fe magnetization, MFe , can be controlled by varying the morphology of the MnAs template via temperature driven stripe formation [11,13]. These results are interesting for potential applications in temperature induced magnetization switching, without applying external fields
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