Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 59: Magnonics III
MA 59.8: Talk
Friday, March 13, 2026, 11:30–11:45, POT/0361
Time domain correlation spectroscopy of thermal and nonequilibrium magnons — •F. S. Herbst1, M. A. Weiss1, C. Runge1, N. Beaulieu2, J. B. Youssef2, A. Leitenstorfer1, M. Lammel1, R. Schlitz1, and S. T. B. Goennenwein1 — 1Department of Physics, University of Konstanz, Germany — 2LabSTICC, CNRS, Université de Bretagne Occidentale, France
Yttrium iron garnet (YIG) is a prototypical material for spintronics and magnonics due to its low magnetic damping and high spin wave propagation velocities. The properties of coherently excited, standing spin waves are well understood. However, much less is known about the interplay between coherently excited magnons and incoherent fluctuations, as schemes simultaneously resolving both coherent and incoherent contributions in a single measurement are scarce. In this work, we probe bismuth doped YIG with femtosecond noise correlation spectroscopy (FemNoC), an optical technique probing magnetization dynamics in the time domain. This method enables us to simultaneously investigate both the thermal magnon noise background and the coherent magnon response induced by microwave excitation. Using a phenomenological model, we can fit both the waveform and amplitude of the experimental data. This step allows us to quantify and disentangle the respective contributions by their correlation signature. Consequently, FemNoC gives access to the absolute magnon number of a magnetic system in the time domain.
Keywords: Bi:YIG; FemNoC; correlation; magnon noise; optical probing