Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 22: Multiferroics I (DF with DS/KR/MA/TT)

MA 22.4: Talk

Wednesday, March 18, 2015, 10:15–10:30, EB 107

Time resolved polarized neutron scattering and dielectric spectroscopy reveal multiferroic domain dynamics in MnWO₄ and TbMnO₃ — •Jonas Stein¹, Daniel Niermann¹, Christoph Grams¹, Max Baum¹, Tobias Cronert¹, Jeannis Leist², Karin Schmalzl³, A Agung Nugroho⁴, Alexander C Komarek⁵, Götz Eckold², Petra Becker⁶, Ladislav Bohatý⁶, Joachim Hemberger¹, and Markus Braden¹ — ¹II. Physikalisches Institut, Uni Köln — ²Institut für Phys. Chemie, Uni Göttingen — ³JCNS at ILL, France — ⁴Institut Teknologi Bandung, Indonesia — ⁵MPI Dresden — ⁶Institut für Kristallographie, Uni Köln

Multiferroic materials are promising for future memory devices with low power consumption. The rise time between two states is a crucial parameter for a possible application and was investigated in the spin spiral multiferroics TbMnO₃ and MnWO₄. Polarized neutron diffraction is able to determine the ratio of chiral domains, which can be controlled by an electric field. Using the stroboscopic technique we follow the reversion of chiral domains in the timescale of a few hundred microseconds to hours. In TbMnO₃ we find a simple logarithmic relation between the rise time and temperature that is fulfilled over 5 decades. Broadband linear and nonlinear dielectric spectroscopy revealed the domain dynamics in the MF phase of MnWO₄. The rise time reaches values in the minute range in the middle of the multiferroic temperature regime at T≈10 K but unexpectedly decays again on approaching the lower, first-order phase boundary at T_N1≈7.6 K.

[1] Niermann et al. PRB 89,134412 [2] Baum et al. PRB 89,144406