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]. Recently the single-pulse switching of various magnetic material (ferrimagnetic, ferromagnetic) within a magnetic spin-valve structure have been demonstrated. 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 a Ferromagnetic (FM) layer can lead to magnetization switching will be presented [7,8]. Finally, magnetization dynamics measurement show that the reversal of the FM layer happens in less than one picosecond which can be modelled [9].

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.

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[2] P. Scheid, et al JMMM 2022 https://doi.org/10.1016/j.jmmm.2022.169596

[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 et al J. Phys. Soc. Jpn 90, 081009 2021

[10] Q. Remy, et al to be published