Energy Efficient Control of Ultrafast Spin Current to Induce Single Femtosecond Pulse Switching of a Ferromagnet

Abstract

New methods to induce magnetization switching in a thin ferromagnetic material using femtosecond laser pulses without the assistance of an applied external magnetic field have recently attracted a lot of interest. It has been shown that by optically triggering the reversal of the magnetization in a GdFeCo layer, the magnetization of a nearby ferromagnetic thin film can also be reversed via spin currents originating in the GdFeCo layer. Here, using a similar structure, it is shown that the magnetization reversal of the GdFeCo is not required in order to reverse the magnetization of the ferromagnetic thin film. This switching is attributed to the ultrafast spin current and can be generated by the GdFeCo demagnetization. A larger energy efficiency of the ferromagnetic layer single pulse switching is obtained for a GdFeCo with a larger Gd concentration. Those ultrafast and energy efficient switchings observed in such spintronic devices open a new path toward ultrafast and energy efficient magnetic memories.

Spin-transport Mediated Single-shot All-optical Magnetization Switching of Metallic Films

“…In this experiment, the composition of Gd used was 33%, where a single GFC layer cannot exhibit single-shot AOS. 70) The MOKE hysteresis loop for the Gd-rich GFC= Cu=CoPt spin-valve is shown in Fig. 8 images after irradiation with fs laser pulses are shown in Fig.…”

“…69) Furthermore, our recent results demonstrated that energyefficient single-shot AOS of FMs can be obtained by increasing the amount of spin-current using a FM=nonmagnetic metal=GFC spin-valve structure. 70) From the experiments and calculations pertaining to the ordering temperature of the FMs in a spin-valve, the mechanism of single-shot AOS of the FMs can be qualitatively explained by the combined effects of ultrafast quenching of magnetization and the transfer of angular momentum from Gd. 71) In this review, we first describe the AOS in ferrimagnetic GFC and the mechanism behind single-shot AOS.…”

Ferrimagnet GdFeCo Characterization for Spin‐Orbitronics: Large Field‐Like and Damping‐Like Torques

“…[2,3] AO-HIS has also been recently observed in TbCo. [4] Nowadays, GdFeCo is used to perform the AO-HIS of Co/Pt [5][6][7] or CoNi/Pt [8] ferromagnetic multilayers. Moreover, it is possible to tune the Dzyaloshinskii-Moriya interaction in thin GdFeCo ferrimagnetic alloys, [9] a relevant property for skyrmions formation.…”

Modeling ultrafast demagnetization and spin transport: the interplay of spin-polarized electrons and thermal magnons

“…Additionally, in noncollinear magnetic systems THz standing spin waves are excited by the spin-transfer torque [5,6]. Moreover, the spin currents can play an assisting role in deterministic all-optical switching [7][8][9][10][11]. In other words, optically induced spin currents provide a versatile tool to manipulate magnetic systems on ultrashort timescales and pave the way towards future spintronic technologies.…”