Modern technology in its development requires a decrease in physical dimensions and at the same time an increase in the speed of operation of devices. Therefore ultrafast manipulation of magnetic ordering is of the great interest [1, 2]. Terahertz radiation is considered as a potentially ultrafast way to switch magnetization since terahertz magnetic field directly couples to the spin degrees of freedom by the Zeeman interaction, which enables a efficient torque acting on the magnetization spin axis [3]. On the contrary, magnetic dynamics can be used for terahertz pulse detection. That is why a convenient analytical description of the terahertz laser pulse and the analysis of its influence on the magnetization dynamics are important tasks.

In this seminar, we present a general theoretical model for the Zeeman torque dynamics under the influence of the ultrashort terahertz laser pulse in the approximation of a low fluence that might be convenient in spin-based terahertz technology since low energy consumption. In addition, we analyze (on the basis of experimental data for fcc cobalt [3] and bcc iron [4, 5]) the possibility of restoring information about the pulse based on the observation of magnetization dynamics.

Our theoretical framework [6] could potentially be used to design new type of terahertz detectors [7] based on the magnetic component of the electromagnetic radiation.

[1] A. Kirilyuk, A. V. Kimel, and T. Rasing, Rev. Mod. Phys. 82, 2731 (2010).
[2] K. Olejnı́k, T. Seifert, Z. Kašpar, V. Novák, P. Wadley, R. P. Campion, M. Baumgartner, P. Gambardella, P. Němec, J. Wunderlich, et al., Science Advances 4, eaar3566 (2018).
[3] M. Shalaby, A. Donges, K. Carva, R. Allenspach, P. M. Oppeneer, U. Nowak, and C. P. Hauri, Phys. Rev. B 98, 014405 (2018).
[4] A. L. Chekhov, Y. Behovits, J. J. F. Heitz, C. Denker, D. A. Reiss, M. Wolf, M. Weinelt, P. W. Brouwer, M. Münzenberg, and T. Kampfrath, Phys. Rev. X 11, 041055 (2021).
[5] A. L. Chekhov, Y. Behovits, U. Martens, B. R. Serrano, T. S. Seifert, M. Wolf, M. Muenzenberg, and T. Kampfrath (2023), in preparation.
[6] I. Korniienko, P. Nieves, and D. Legut, Phys. Rev. Lett. (under review Q1/2023).
[7] R. A. Lewis, J. Phys. D: Appl. Phys., 52 , 433001, (2019).