1. Salle de séminaire, IJL-Vandoeuvre Entrée 2A 4éme Etage
Jeudi 4 Mai 2017 à 10h00
Salle de séminaire, IJL-Vandoeuvre Entrée 2A 4éme Etage
Investigation of ultrafast magnetization dynamics via pump-probe technique for materials with large perpendicular magnetic anisotropy
Dr. Satoshi Iihama ( AIST – Univ Lorraine)
Magnetic materials with large perpendicular magnetic anisotropy (PMA) has attracted attention for the high density magnetic recording. Recently, it was demonstrated that magnetization for ferromagnetic FePt and [Co/Pt] film having large PMA can be switched by the optical femtosecond laser pulse, which indicates the optical manipulation of magnetization will be a promising technique to realize ultrahigh density and ultrafast magnetic recording [1]. We had focused on the investigation of ultrafast magnetization dynamics via pump-probe technique for materials with large PMA such as L10-FePt and FePd alloy [2]. Main body of this presentation will focus on ultrafast magnetization dynamics for L10-FePt and FePd alloy films.
When femtosecond laser pulse is incident to the film, magnetization reduces very fast within sub-picosecond time scale, called ultrafast demagnetization. And then magnetization precession can be excited followed by the ultrafast demagnetization. First, this presentation will give how fast magnetization reduces for the materials of L10-FePt and FePd. Next, we discuss the precessional magnetization dynamics and damping for L10-FePt and FePd films. Precessional frequency and relaxation time can be explained by the Landau-Lifshitz Gilbert equation with considering extrinsic damping mechanism. The details of the analysis and damping parameters for these materials will be discussed in the presentation.
Finally, whereas it is unrelated to the topic mentioned above, our recent results, propagating spin-wave induced by femtosecond laser pulse in NiFe film [3], spin-orbit torque induced by anomalous Hall effect in CoFeB film [4], will be slightly introduced in the presentation.
[1] C-H. Lambert et al. Science, 345, 1337 (2014).
[2] S. Iihama et al. J. Phys. D: Appl. Phys. 49, (2016), Phys. Rev. B, 94, (2016).
[3] S. Iihama et al. Phys. Rev. B, 94, (R) (2016), A. Kamimaki et al. submitted.
[4] S. Iihama et al. in-preparation.
Séminaire de la priorité thématique:
Matériaux Artificiels Nanostructurés