Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 48: Magnonics II
MA 48.2: Talk
Thursday, March 12, 2026, 15:15–15:30, HSZ/0004
Long-range propagating paramagnon-polaritons in organic free radicals — •Sebastian Knauer1, Roman Verba2, Rostyslav O. Serha1,3, Denys Slobodianiuk2, David Schmoll1,3, Andreas Ney4, Sergej O. Demokritov5, and Andrii V. Chumak1 — 1Faculty of Physics, University of Vienna, 1090 Vienna, Austria. — 2V. G. Baryakhtar Institute of Magnetism of the NAS of Ukraine, 03142 Kyiv, Ukraine. — 3Vienna Doctoral School in Physics, University of Vienna, 1090 Vienna, Austria. — 4Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Universität, 4040, Linz, Austria. — 5Institute for Applied Physics, University of Münster, 48149 Münster, Germany.
Magnetic materials can host magnons below their Curie or Néel temperature, whereas in their paramagnetic phase, only short-range paramagnons are observed. We show that the organic free radical TEMPO supports long-range coherent spin dynamics well above its Néel temperature. Using all-electrical propagating spin-wave spectroscopy with on-chip microwave lines and external fields, we observe coherent excitations up to 23 GHz with group velocities above 100 km s−1 over 8 mm, exceeding calculated paramagnon velocities. Dispersion and pulse-propagation modelling identify these modes as paramagnon-polaritons, hybrid spin-photon excitations guided by the TEMPO column. This establishes organic free radicals as tunable paramagnetic magnonic media for microwave circuitry, spintronics, and high-frequency classical and quantum information processing [1].
[1] S. Knauer et al., RS, 2025 DOI: 10.21203/rs.3.rs-7990671/v1
Keywords: Paramagnonics; Propagating Spin-Wave Spectroscopy; Millikelvin Temperature Magnonics