Dresden 2017 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 15: Ferroics - Domains, Domain Walls and Skyrmions III

DF 15.1: Topical Talk

Mittwoch, 22. März 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)