Inertial magnetization dynamics near THz frequencies
Mercredi 24 juin 2015 11:00
- Duree : 1 heure
Lieu : Salle "Remy Lemaire" K 223 (1er étage) bât. K de l’Institut Néel/CNRS - 25 rue des martyrs 3800 Grenoble
Orateur : Prof. William BAILEY (Columbia University, USA and Nanosciences Foundation Chair of Excellence)
Abstract :
A central assumption of the Landau-Lifshitz-Gilbert (LLG) equation is that magnetization dynamics are inertialess. Magnetization then responds to a step applied field with an instantaneous change in rotational speed, and thus with infinite acceleration. This assumption has been predicted to break down at short enough time scales, somewhere below one picosecond. We have tested for the existence of novel, inertial terms to magnetization dynamics using very high-frequency ferromagnetic magnetic resonance (FMR), up to 334 GHz, at the Grenoble high magnetic field lab LNMCI-G (CNRS). We find that terms to the motion quadratic in frequency are present in typical ferromagnetic device thin films, Ni81Fe19 (Py) and Co, near room temperature. The results demonstrate the use of magnetic resonance to access ultrafast ( 100 fs) magnetization dynamics, and may perhaps open up new possibilities for high-speed switching.
Joint work with A.-L. Barra, LNMCI/CNRS and U. Ebels and S. Auffret, SPINTEC/CEA.
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Discipline évènement : (Physique)
Entité organisatrice : (Fondation Nanosciences)
Nature évènement : (Séminaire)
Site de l'évènement : Polygone scientifique
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