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MA: Fachverband Magnetismus
MA 58: Computational Magnetism II
MA 58.11: Vortrag
Freitag, 13. März 2026, 12:15–12:30, POT/0151
Acoustic Wave Group Velocity under Magnetic Field — •Dominik Legut1,2, Ievgeniia Korniienko1, and Pablo Nieves3 — 1IT4Innovations, VSB-TU Ostrava, Ostrava, Czechia — 2Charles University, Prague, Czechia — 3University of Oviedo, Oviedo, Spain
Recently, we derived a spin-lattice model for ferromagnetic cubic crystals[1]. Then we analyzed the effect of the magneto-elasticity on the group velocities for high symmetry directions[2]. Here we present a different approach to determine the group velocity of the acoustic waves in any crystals and under the effects an external magnetic field for cubic and hexagonal symmetry. The group velocity is obtained by calculating Christoffel matrix elements and their partial derivative with respect to the phase velocity direction, and inserting them in an analytical expression for the group velocity. The effect of that external magnetic field is computed through the induced effective corrections to the elastic tensor which depend on the magnetic susceptibility tensor and the magnetoelastic constants. We present examples of dry sandstone, cubic CoPt and hcp Co to show complex landscapes of fractional change in group velocity as a function of ray direction, as well as a field dependence consistent with the Simon effect[3]. We have developed web-based applications where these effects can be analyzed and visualized in 3D[4].
[1] P. Nieves et al.: Phys. Rev. B 103, 094437 (2021)
[2] P. Nieves et al.: Phys. Rev. B 105, 134430 (2022)
[3] I. Korniienko, et al.: Results in Physics, 73, 108264 (2025)
[4] P. Nieves et al.:, SoftwareX 33, 102472 (2026)
Keywords: sound wave velocity; group velocity; magnetoelastic effect; ferromagnetism