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Group Seminar 2021/22

Category
Group Seminar
Date
Date
Thursday 21 April 2022, 14:00-15:00
Location
William Bragg, LT 2.37
Speaker
Prof Stéphane Mangin
Institution
Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, France
Title
Femto-second to pico-second laser pulse to switch magnetization

Abstract:

During the last decade all-optical ultrafast magnetization switching in magnetic material thin film without the assistance of an applied external magnetic field has been explored [1,2]. It has been shown that femto-second light pulses can induce magnetization reversal in a large variety of magnetic materials [3,4]. However, so far, only certain particular ferrimagnetic thin films exhibit magnetization switching via a single femto-second optical pulse. All optical helicity dependent switching of a ferromagnetic layer could be demonstrated for a low number of pulses [5]. We will present the single-pulse switching of various magnetic material (ferrimagnetic, ferromagnetic) within a magnetic spin-valve structure and further show that the four possible magnetic configurations of the spin valve can be accessed using a sequence of single femto-second light pulses. Our experimental study reveals that the magnetization states are determined by spin-polarized currents generated by the light pulse interactions with the GdFeCo layer [6]. A detail study showing how spin-polarized currents are generated and how they interact with magnetic layers (Ferromagnetic or Ferrimagnetic) to lead to magnetization switching will be presented [7,8].

Figure 1
Sketch of a spin-valve structure used to
demonstrate femto-second single pulse
switching of each magnetic layer
independently. The generation of
femto-second spin current is shown to play a
major role.

[1] C. D. Stanciu, et al Phys. Rev. Lett. 2007, 99, 047601
[2] I. Radu et al, Nature 2011, 472, 207
[3] S. Mangin, et al, Nat. Mater. 2014, 13, 286
[4] C. -H. Lambert, et al Science 2014, 345, 1337
[5] G. Kichin, et al Phys. Rev. App. 12 (2), 024019 2019
[6] S. Iihama et al Adv Matter 1804004 2018
[7] Q. Remy, et al Adv. Sci. 2001996 2020
[8] J. Igarashi, et al Nano. Lett. 20, 12, 8654–8660 2020
[9] S. Iihama, J. Phys. Soc. Jpn 90 081009 2021