Dresden 2020 – wissenschaftliches Programm
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MA 32.4: Vortrag
Mittwoch, 18. März 2020, 10:15–10:30, HSZ 401
Evidence for existence of electromagnon in the multiferroic phase of Cu(II)O: A novel type polarized neutron scattering study at the thermal triple-axis spectrometer PUMA@FRM II — •Avishek Maity1,2, Steffen Schwesig1, Fabian Ziegler1, Oleg Sobolev1, and Götz Eckold1 — 1Institute for Physical Chemistry, Georg-August-University of Göttingen, 37077 Göttingen, Germany — 2Heinz Maier-Leibnitz Zentrum (FRM II), Technical University of Munich, 85748 Garching, Germany
Since the spontaneous electric polarization was discovered in one of its anti-ferromagnetic (AFM) phases AF2 with Tn=230 K , Cu(II)O regained the focus of research as a model compound for high-temperature type-II multiferroics. The ferroelectricity in the AF2 phase is induced by the cycloidal spin arrangement due to an anisotropic super-exchange interaction (DM) leading to an interesting coupling between spinwave and optical phonon namely electromagnon which is the elementary excitations involving in the magnetoelectric coupling . Here we present the results from polarized neutron scattering to characterize low-energy magnetic excitations in the multiferroic phase of CuO using a novel type of polarization analysis available at the thermal triple-axis spectrometer PUMA@FRM II allowing the simultaneous detection of spinflip and non-spinflip scattering. We have determined energy gaps of several magnon modes and evidenced the signature for the existence of electromagnons near 3 and 13 meV .
Refs:  Kimura et al., Nat. Mat. 7, 291 (2008).  Cao et al., Phys. Rev. Lett. 114, 197201 (2015).  Maity et al. 2019 (submitted).