Séminaire LCPMR | Diego Turenne "Ultrafast response of spin and lattice in FePt nanoparticles"
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Le 05 déc. 2024
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14:30 - 15:30
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Séminaire
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Sorbonne-Université
Campus Pierre et Marie Curie
UFR de chimie tour 32-42
Salle 101
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Jal Emmanuelle
| SÉMINAIRE | Personnalité invitée |
| Titre |
ULTRAFAST RESPONSE OF SPIN AND LATTICE IN FePt NANOPARTICLES |
| Présenté par | |
| Affectation | Uppsala, University, Sweden |
| Résumé | Out of equilibrium dynamics driven by an ultrafast optical pulse are a topic of study in several areas of physics. Among those, ultrafast magnetism vies to describe how spin, an inherent property of electrons, is transferred at ultrafast time scales. Among the many materials studied, FePt nanoparticles have been the subject of scientific interest in the past years due to its high spin orbit coupling that strongly couple lattice and spin and its technological applications. During my presentation, I will present the results I have obtained during my thesis work: Through ultrafast resonant and off-resonance small angle scattering, the presence of a small, sub-10nm magnetic bubble forms after complete demagnetization by high fluence optical laser. At lower fluences, the lattice response of the system is tracked through electron diffraction where the Pt at Fe sub-lattices respond differently, leaving the crystal slightly away from perfect Bragg conditions. Finally, using diffuse scattering, the transient phonon populations are probed and are shown to have different response times, showcasing the non-thermal nature of the phenom during the first few picoseconds. These results open the possibility for new applications for the material by making FePt nanoparticles a candidate to study for THZ antenna applications. |
| Contact LCPMR | Emmanuelle Jal |