Regensburg 2022 – scientific programme
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MA: Fachverband Magnetismus
MA 35: Poster 2
MA 35.12: Poster
Thursday, September 8, 2022, 16:00–18:00, P4
VSM and EPR characterization of GGG at ultralow temperatures — •R. O. Serha1, S. Knauer1, D. Schmoll1, K. Davidkova3, Q. Wang1, B. Budinská1, O. V. Dobrovolskiy1, V. E. Demidov2, M. Urbánek3, S. O. Demokritov2, and A. V. Chumak1 — 1University of Vienna, Faculty of Physics, Boltzmanngasse 5, A-1090 Vienna, Austria — 2Boltzmanngasse 5Institute for Applied Physics and Center for Nonlinear Science, University of Muenster, Corrensstrasse 2-4, D-48149 Muenster, Germany — 3CEITEC BUT, Brno University of Technology, Purkynova 123, 612 00 Brno, Czech Republic
Magnons, the quanta of spin-waves, also exist in paramagnetic materials and are known as paramagnons. Paramagnon properties are governed by the exchange interactions, which do not vanish above Curie/Neel temperature and the dipolar interactions. Here we present our results on the investigation of electron paramagnetic resonance (EPR) spectroscopy in gadolinium gallium garnet (GGG) and DPPH bulk slabs in a wide range of temperatures down to 20 mK. GGG is one of the materials of choice, as Gd3+ ions have a large spin S = 7/2 and its saturation magnetization is about Ms = 800 kA/m. Millikelvin temperatures allow reaching the saturation of the GGG magnetization, by applying magnetic fields of hundreds mT. However, the EPR linewidth of GGG is strongly influenced by the phenomenon of dipolar broadening, while DPPH is known to have a very narrow resonance line. These studies form an initial step toward investigations of long-propagating paramagnons.