Controlling order parameters (magnetic, ferroelectric etc) on ultimate time and length scales is a key quest in condensed matter research. This is particularly true for the field of magnetism and spintronics [1,2] where besides a fundamental scientific interest there is an exciting potential for technological applications in, e.g., high-speed magnetic logic and magnetic storage devices. Ultrafast laser pulses are very appealing tools in this context [3] as it has been shown to be able to photo-drive, measure and eventually control magnetic states of matter on ultrashort timescales [4,5]. Prominent examples of how ultrashort bursts of light can affect the magnetic order parameter are, for instance, the ultrafast demagnetization [6], generation of coherent spin dynamics at THz frequencies [7] and all-optical magnetization switching (AOS) [1-5], to name just a few. Despite of all these breakthroughs, the ultimate speed of controlling the spins remains a largely unexplored issue and yet to be demonstrated. Here, I will present the latest developments in our projects on ultrafast magnetism employing selective excitations and probing of spins using time- resolved techniques spanning the entire spectral range from soft X-rays to THz radiation. A particular focus will be placed on driving deterministic magnetization switching processes using these novel light sources. Future plans targeting light-driven spintronics phenomena at THz to PHz clock rates will be discussed as well.
[1] A. Kirilyuk, A.V. Kimel and Th. Rasing, Rev. Mod. Phys. 82, 2731 (2010)
[2] K. Carva, P. Balasz and I. Radu, Laser-induced Ultrafast Magnetic Phenomena (Invited Review), Handbook of Magnetic Materials 26, 29-463 (2017)
[3] I. Radu, in The 2021 Roadmap on Ultrafast Spectroscopic Probes of Condensed Matter, J. Phys. Cond. Mat. 33, 353001 (2021)
[4] C.D. Stanciu et al., Phys. Rev. Lett. 99, 047601 (2007)
[5] I. Radu et al., Nature 472, 205 (2011)
[6] F. Siegrist et al., Nature 571, 240-244 (2019)
[7] T. Kampfrath et al., Nature Photonics 5, 31-34 (2011)

https://www.spintec.fr/seminar-light-driven-ultrafast-magnetic-phenomena-towards-petahertz-spintronics/