Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 28: Magnonics 2

MA 28.9: Vortrag

Donnerstag, 8. September 2022, 11:30–11:45, H43

Experimental Detection of Magnon Noise Enhancement near Spin Reorientation in Sm_0.7Er_0.3FeO₃ — •Marvin Weiss¹, Andreas Herbst¹, Julius Schlegel¹, Martin Evers¹, Tobias Danegger¹, Andreas Donges¹, Makoto Nakajima², Sebastian T. B. Goennenwein¹, Alfred Leitenstorfer¹, Ulrich Nowak¹, and Takayuki Kurihara^1,3 — ¹Department of Physics, University of Konstanz — ²ILE, Univ. Osaka — ³ISSP, Univ. Tokyo

Disentangling intrinsic quantum mechanical interactions and thermal fluctuations is especially important for understanding and controlling magnetic phase transitions. In solids, the dynamics of thermal fluctuations of elementary excitations typically proceed on a picosecond timescale. Although optical pump-probe experiments give access to this range, the experimental detection of ultrafast spin fluctuations remains largely unexplored due to their incoherent character. We investigate the elementary dynamics of thermally excited incoherent magnons in the time domain with femtosecond resolution. The experiments are enabled by a novel setup that allows for extracting the correlation of the pulse-to-pulse polarization fluctuations between two temporally and spectrally separated femtosecond probe pulses that transmit through the sample. As a proof-of-principle demonstration, we study the critical phenomena around the spin reorientation transition (SRT) of the orthoferrite Sm_0.7Er_0.3FeO₃. Distinct changes of magnon noise amplitude and dynamics are mapped out around the SRT.