Regensburg 2019 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 7: Multiferroics

KFM 7.2: Talk

Monday, April 1, 2019, 15:20–15:40, H47

Domain dynamics in LiCuVO₄: Evidence for polarized nanoregions — •Christoph P. Grams¹, Severin Kopatz¹, Daniel Brüning¹, Sebastian Biesenkamp¹, Petra Becker², Ladislav Bohatý², Thomas Lorenz¹, and Joachim Hemberger¹ — ¹University of Cologne, Institute of Physics II, Zülpicher Str. 77, 50937 Cologne, Germany — ²University of Cologne, Institute of Geology and Mineralogy, Section Crystallography, Zülpicher Str. 49b, 50674 Cologne, Germany

LiCuVO₄ is a model system of a 1D spin-1/2 chain that enters a multiferroic planar spin-spiral ground state below its Néel temperature of 2.4 K with electric polarization along the a axis. With external magnetic fields in c direction T_N can be suppressed down to 0 K at 7.4 T.

Here we report dynamical measurements of the polarization from P(E)-hysteresis loops, magnetic field dependent pyro-current and non-linear dielectric spectroscopy as well as thermal expansion and magnetostriction measurements at very low temperatures. Our measurements find a sizable magnetoelastic coupling in LiCuVO₄ that strongly influences all observed quantities. Most striking is the observation of a growth dimension d ≈ 0.25, i.e. strong pinning of the domain walls, from the non-linear polarization dynamics. Further analysis finds the domain sizes to be in the nm range.