Regensburg 2019 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 16: Multiferroics and Magnetoelectric coupling II (joint session MA/KFM)

KFM 16.2: Vortrag

Freitag, 5. April 2019, 09:45–10:00, H39

Coupled electric and magnetic domains and domain walls in h-RMnO₃ at the microscale — •Marcela Giraldo, Thomas Lottermoser, and Manfred Fiebig — ETH Zurich, Switzerland.

Fundamental understanding of the cross-coupling between ferroic orders at the level of domains and domain walls is crucial for the manipulation of multiferroics. It was shown for the first time on h-RMnO₃ that coupling between ferroelectricity and antiferromagnetism –with order parameters P and l, respectively– occurs in a type-I multiferroic where ferroic orders emerge independently. At the macroscopic scale, it was observed that the antiferromagnetic domain pattern (l) is defined by two independent domain patterns formed by P and the multiferroic order parameter Pl [1]. Albeit, coupling on the microscopic regime, on the level of the ferroelectric vortex domains which are characteristic for these materials has remained under debate. For the first time, we investigate the coupling between electric and magnetic domains in h-RMnO₃ on the microscopic scale using second-harmonic microscopy. We reveal that two of the three order parameters (P, l and Pl) change their sign simultaneously at every domain wall while the third one retains its sign. This confirms the earlier observation [1] that P and Pl form independent domain patterns. In addition, we show a new type of domain wall where P and Pl change their sign, while l remains constant. Our observations solve the open debate about coupling of domains and domain walls at the microscale and add new findings to understand the unique coupling nature in a type-I multiferroic.

[1] M. Fiebig et al., Nature 419, 818 (2002).