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Dynamic Interplay between Magnetization and Surface Acoustic Waves in Magnetostrictive Fe(1−x) Ga(x) Thin Films

Abstract : Recently, lot of efforts have been devoted to control the magnetization in nano-structures by means other than external magnetic field to achieve device miniaturization, as it is difficult to handle the magnetic field at low lateral dimensions. On the other hand, a new road emerged towards the wave based computing by employing spin waves (SWs). The advantages, that SWs offer for the data processing are nm wavelength as compared to the electromagnetic waves in the same frequency range (GHz-THz) and the absence of Joule heating. A possibility exists to use Surface Acoustic Waves (SAWs), in other words, dynamic strain, to induce magnetization dynamics or to control spin waves. This is possible due to a very fundamental property of magnetic bodies, the magneto-elastic coupling, that is when magnetization orientation and strain are coupled. This thesis focuses on the phenomenology of the magneto-elastic interaction in thin epitaxied films of magnetostrictive Fe(0.8)Ga(0.2). We performed a systematic experimental study of the magneto-elastic interactions in thin films of different thicknesses and magnetic structures. We also developed two phenomenological models in order to interpret our results. An important result of this study is that we are able to extract the magneto-elastic and the magnetic anisotropy constants by acoustic means. The thesis has also a strong technological component. One aim was to efficiently excite surface acoustic waves in GHz frequency range (1-5 GHz) on GaAs piezoelectric substrates in order to observe the resonant interaction with thermal spin waves. We also managed to excite spin waves in thin epitaxied magnetostrictive layers, using RF antennas. We report preliminary measurements on this interaction that were performed with Brillouin light scattering (BLS) and micro BLS techniques in collaboration with the GHOST laboratory in Perugia, Italy.
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Contributor : Carolyna Hepburn <>
Submitted on : Saturday, November 17, 2018 - 3:27:00 PM
Last modification on : Friday, March 22, 2019 - 1:39:20 AM
Long-term archiving on: : Monday, February 18, 2019 - 12:18:06 PM

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  • HAL Id : tel-01916238, version 1

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Carolyna Hepburn. Dynamic Interplay between Magnetization and Surface Acoustic Waves in Magnetostrictive Fe(1−x) Ga(x) Thin Films. Materials Science [cond-mat.mtrl-sci]. Paris Institute of Nanosciences (INSP), 2017. English. ⟨tel-01916238⟩

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