Alexey Kimel

Abstract: Ultrafast spin dynamics in antiferromagnets is paradoxical.  While commonly accepted Curie-Neumann’s principle states that “the symmetries of the causes are to be found in the effects” [1] and implies that a magnetic field cannot control antiferromagnetic Néel vector, rapidly changing THz magnetic field appears to “violate” this principle and can effectively excite spins in antiferromagnets . In this ultrafast regime, laser-induced spin dynamics in antiferromagnets is intrinsically non-linear [2-4], where new channels of spin-lattice interaction open-up [2,3], the principle of superposition fails, i.e. 1+1>2 [4], and antiferromagnets appear to host even more channels to excite spins [5-7] than one can find in ferromagnets. We will review recent progress in ultrafast antiferromagnetic spin dynamics, highlight the recently discovered mechanism enabling control of antiferromagnetic spins by a THz electric field [6], and discuss the conditions required for reliable writing of stable antiferromagnetic bits [8].

[1]     P. Curie, “On Symmetry in Physical Phenomena”, J. Phys. Theor. Appl., 393–415 (1894).

[2]     E. A. Mashkovich et al, “Empowering Control of Antiferromagnets by THz-Induced Spin Coherence”, Science 374, 1608-1611 (2021).

[3]     T. Metzger et al, “Magnon-phonon Fermi resonance in antiferromagnetic CoF₂”Nature Communications 15, 5472 (2024).

[4]     T. G. H. Blank et al, Phys. Rev. Lett. 131, 096701 (2023).

[5]     Y. Behovits et al, “Terahertz Néel spin-orbit torques drive nonlinear magnon dynamics in antiferromagnetic Mn₂Au” Nature Communications 14, 6038 (2023).

[6]     V. Bilyk et al, “Control of spins in collinear antiferromagnet Cr₂O₃ by terahertz electric fields”Newton 1, 6100132, (2025).

[7]    R. M. Dubrovin, A. V. Kimel, A. K. Zvezdin, “Competition between terahertz magnetoelectric and Néel spin-orbit torque driven spin dynamics in metallic antiferromagnets” Phys. Rev. B 112, 064402 (2025).

[8]    N. Khokhlov et al., in preparation

Biography:

Alexey Kimel obtained his PhD from the Ioffe Institute (St. Petersburg, Russia) and joined the Institute for Molecules and Materials (IMM) at Radboud University as a postdoctoral researcher in 2002.He was subsequently appointed Assistant Professor in 2007, Associate Professor in 2013, and Full Professor in 2017.He pioneered ultrafast spin dynamics in antiferromagnetic materials [PRL89, 287401 (2002), Nature 435 655–657 (2005)] and his works in a large extent defined the development of ultrafast magnetism during the last two decades. He is a co-inventor of ultrafast all-optical magnetic recording [PRL99, 047601 (2007)] and inertia of spins in antiferromagnets [Nature-Physics5, 727–731 (2009)], as a recognized world-leader in the field he obtained several prestigious research grants (Veni2004, Vidi2006, Vici2017, ERC-SG2010, Russian MegaGrant-2013, ERC-AG2022).Starting from September 2025, he serves as the Research Director of the Institute for Molecules and Materials.

Kazuto

Yamanoi Kazuto

Department of Physics, Keio University, Kanagawa, Japan