SFB 1238 | October 29, 14:30
Inertial effects in spin dynamics in ferromagnets: a quantitative framework for sub-THz magnonics
The phenomenon of additional high-frequency (sub-THz/THz) spin dynamics resonance in ferromagnets arising due to the inertia of magnetization has been recently demonstrated both theoretically [1] and subsequently by experimental observation in permalloy, CoFeB and cobalt [2,3]. Non-resonant excitation of magnetic nutation using ultrashort laser pulses was also shown [4]. The existence of a sub-THz resonant frequency in ferromagnetic materials, together with the capability to excite magnetization nutation coupled to its precession, broadens the potential range of applications of ferromagnets in ultrafast magnetism and sub-THz magnonics.
In this talk I will show that in addition to a direct detection of nutation resonance, the inertial effects can be resolved using ferromagnetic resonance [5,6]. We derive the full tensor of magnetic susceptibility analytically and address the impact of material parameters, including the Gilbert damping constant, the inertial relaxation time, and the applied magnetic field, on the intensity and linewidth of coupled precession and nutation resonances. The present work provides a guideline for identifying materials that allow the detection of inertial effects in ferromagnets using time or frequency domain experiments.
[1] M.-C. Ciornei, J. Rubi, J.-E. Wegrowe, Physical Review B, Vol. 83, 020410 (2011)
[2] K. Neeraj, N. Awari, S. Kovalev et al., Nature Physics, Vol. 17, 245 (2021)
[3] V. Unikandanunni, R. Medapalli, M. Asa et al., Physical Review Letters, Vol. 129, 237201 (2022)
[4] A. De, J. Schlegel, A. Lentfert et al., Physical Review B, Vol. 111, 014432 (2025)
[5] M. Cherkasskii, I. Barsukov, R. Mondal et al., Physical Review B, Vol. 106, 054428 (2022)
[6] J. Wiemeler, M. Farle, A. Semisalova, Physical Review B, Vol. 112, 094433 (2025)
University of Duisburg-Essen
PH2
Contact: Evgeny Mashkovich