Speaker
Description
Advances in the development of ultrafast lasers have made picosecond ultrasonics a novel research field which alows to generate and detect acoustic waves with frequencies up to terahertz and wavelengths down to nanometers. Picosecond laser ultrasonics is successfully applied for experimentally study of nanostructures, adhesion of monolayers, and profile inhomogeneity [1, 2]. However, due to the complexity of studied phenomena, impressive experimental achievements [3, 2] face limited theoretical descriptions and modeling of the laser-induced elastic response. The situation becomes even more crucial in the case of ferromagnetic materials due to the simultaneous magnetic degree of freedom interaction with the laser radiation and coupling with the elastic degree of freedom. In other words, due to the laser-induced ultrafast demagnetization process, the magnetic subsystem can provide its own contribution to the elastic stress.
In our work we perform an approach to atom-resolved study on the basis of atomistic spin-lattice simulations for laser-induced elastic response in the feromagnetic fcc Ni, which alows us both to calculate the lattice elastic response including ultrafast thermal expansion and to characterize the magnetic contribution to stress in this material [4]. Among the advantages of the proposed 3D atomistic model is the ability to create close to realistic structures with atomic resolution, defects, interfaces, given crystal orientations in layers, and the possibility to obtain the full strain and stress tensor components, which makes the proposed theoretical approach useful for further interpretations of experiments in the picosecond ultrasonics, as well as for providing other required parameters (like ultrafast thermal expansion coefficient) in micromagnetic models of picosecond timescale.
Acknowledgement:
This work was supported by the projects e-INFRA CZ (ID No. 90254) and QM4ST (No. CZ.02.01.01/00/22_008/0004572) by the Ministry of Education, Youth and Sports of the Czech Republic, and also by Czech Science Foundation of the Czech Republic by Grant No. 22-35410K. P.N. acknowledges support by Grant No. MU-23-BG22/00168 funded by the Ministry of Universities of Spain. A.F. acknowledges funding from the Spanish Ministry of Science and Innovation (Grants No. PID2022-139230NB-I00 and No. TED2021-132074B-C32) the Diputación Foral de Gipuzkoa (Project No. 2023-CIEN-000077-01). Research was conducted in the scope of the Transnational Common Laboratory (LTC) Aquitaine-Euskadi Network in Green Concrete and Cement-based Materials. R.I. acknowledges financial support from the project MAGNES funded by the Principality of Asturias Government (Grant No. AYUD/2021/51822) and from the project RADIAFUS V, funded by the Spanish Ministry of Science and Innovation (Grant No. PID2019-105325RB-C32).
References:
[1] T. Saito, O. Matsuda, and O. B. Wright, Phys. Rev. B 67, 205421 (2003).
[2] M. Mattern, A. von Reppert, S. P. Zeuschner, et al., Photoacoustics 31, 100503 (2023).
[3] O. Matsuda, M. C. Larciprete, R. Li Voti, and O. B. Wright, Ultrasonics 56, 3 (2015).
[4] I. Korniienko, P. Nieves, A. Fraile, R. Iglesias, D. Legut, Phys. Rev. Research 6, 023311 (2024).
