Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Ultrafast Magnetization Effects 1

MA 8.10: Vortrag

Montag, 5. September 2022, 17:15–17:30, H37

Spin fluctuations around a reorientation transition in Sm_0.7Er_0.3FeO₃ — •Julius Schlegel¹, Martin Evers¹, Tobias Dannegger¹, Andreas Donges¹, Marvin Weiss¹, Takayuki Kurihara², Sebastian T.B. Goennenwein¹, and Ulrich Nowak¹ — ¹Department of Physics, University of Konstanz — ²ISSP, University of Tokyo

The competition between thermal fluctuations, spin-spin interactions and magnetic anisotropies can lead to various magnetic phase transitions. For example the antiferromagnetic orthoferrite Sm_0.7Er_0.3FeO₃ undergoes a reorientation transition at approximately room temperature. On the basis of an atomistic spin model and the Landau-Lifshitz-Gilbert equation of motion we numerically calculate the time evolution of the magnetization around the reorientation transition on a timescale from picoseconds up to one nanosecond and investigate the thermal fluctuations of the magnetization. By Fourier-transforming the time dependent magnetization we find that the spectra of the noise are temperature dependent and change significantly while going through the reorientation. We also observe several resonances in the spectra. By means of analytical calculations based on linear spin wave theory these peaks can be assigned to the different modes of a model with four sublattices.

Finally, these results are compared to current experimental data from spin noise measurements.