Dresden 2026 – scientific programme

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MA: Fachverband Magnetismus

MA 38: Ultrafast Magnetization Effects II

MA 38.8: Talk

Wednesday, March 11, 2026, 17:00–17:15, POT/0361

Field-tuning of ultrafast magnetization fluctuations in Sm_0.7Er_0.3FeO₃ — •Julius Schlegel¹, Marvin Alexander Weiss¹, Daniel Anić¹, Emil Steiner¹, Franz Stefan Herbst¹, Makoto Nakajima², Takayuki Kurihara³, Alfred Leitenstorfer¹, Sebastian T.B. Goennenwein¹, and Ulrich Nowak¹ — ¹Department of Physics, University of Konstanz, Germany — ²Institute of Laser Engineering, Osaka University, Japan — ³Department of Basic Science, The University of Tokyo, Japan

The missing stray field and the vanishing net magnetization make it challenging to investigate antiferromagnetic dynamics experimentally. Nevertheless, thermal magnetization fluctuations persist in antiferromagnets and can be exploited to gain insights into their dynamics [1].

In this work, we investigate these fluctuations in the canted antiferromagnet Sm_0.7Er_0.3FeO₃ under the influence of an external magnetic field [2]. Using femtosecond noise-correlation spectroscopy combined with atomistic spin-dynamics simulations, we examine the spin noise in the vicinity of the magnetic reorientation transition.

We demonstrate that the external magnetic field suppresses characteristic features of critical fluctuations, such as a diverging noise amplitude. Moreover, it enhances the quasi-ferromagnetic magnon frequency near the reorientation transition. Our results offer a means to tune ultrafast spin fluctuations via experimentally accessible external parameters.

[1] M. A. Weiss et al., Nat. Commun. 14, 7651 (2023).

[2] M. A. Weiss et al., arXiv:2509.26084 (2025)

Keywords: Spin noise spectroscopy; Atomistic spin dynamics simulation; Antiferromagnetic magnons; Reorientation transition