Dresden 2017 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 15: Ferroics - Domains, Domain Walls and Skyrmions III
DF 15.1: Topical Talk
Wednesday, March 22, 2017, 15:00–15:30, WIL B321
Domain and fluctuation dynamics in magnetoelectric multiferroics — •Joachim Hemberger — Institute of Physics II, University of Cologne, Germany
Multiferroic systems comprise hybrid order parameters which couple e.g. non-collinear spin structures to ferroelectric polarization. This talk raises the question concerning the the dynamics of the corresponding fluctuations and discusses results for exemplary magnetoelectric systems on the basis of broadband linear and non-linear dielectric spectroscopy.
E.g. in MnWO4 one observes a critical slowing down of a magnetoelectric soft-mode above the multiferroic transition [1], while the dielectric response within the ordered phase is dominated by the dynamics of domains [2]. Thus both electric field driven phenomena resemble the behavior of canonical ferroelectrics, but an analysis of the corresponding dynamical exponents reveals differences reflecting the magnetic nature of the underlying order parameter.
Similar findings can be reported for other spin-spiral multiferroics like TbMnO3, Ni3V2O8, or even the spin chain LiCuVO4 effected by quantum fluctuations. In addition, the merely magnetic field induced domain and fluctuation dynamics in the non-multiferroic but linear magnetoelectric TbPO4 shall be discussed.
[1] D. Niermann, C.P. Grams, P. Becker, L. Bohatý, H. Schenck, and J. Hemberger, Phys. Rev. Lett. 114, 037204 (2015)
[2] D. Niermann, C.P. Grams, M. Schalenbach, P. Becker, L. Bohatý, J. Stein, M. Braden, and J.H., Phys. Rev. B 89, 134412 (2014)