Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 29: Multiferroics and Magnetoelectric Coupling (joint session MA/KFM)

KFM 29.6: Vortrag

Donnerstag, 8. September 2022, 16:15–16:30, H47

Magnetoelectric domains and topological defects in hexagonal manganites — •M. Giraldo, Q. N. Meier, A. Bortis, D. Nowak, N. A. Spaldin, M. Fiebig, M. C. Weber, and Th. Lottermoser — Department of Materials, ETH Zurich

Domains and domain walls reflect the different interdependence of magnetic and electric order in multiferroics. For example, in type-II multiferroics, magnetic and electric domain patterns are one-to-one linked, whereas in type-I multiferroics, magnetic and electric domain morphologies can be different, and their coupling no longer mandatory. We show -- using experiment and theory -- that multiferroics with separately emerging magnetic and electric order can have a strong bulk magnetoelectric coupling even though the leading magnetoelectric cross-coupling is symmetry-forbidden. We show, taking ErMnO3 as example, that the structural distortions that lead to the ferroelectric polarization also break the balance of the competing superexchange contributions. The resulting bulk coupling leads to novel types of topological defects, like magnetoelectric domain walls and multifold vortex-like singularities. We argue that the apparent independence of magnetic and electric orders in type-I multiferroics leads to uncommon phenomena, not open to the type-II class, which can open additional degrees of freedom for the future control of their magnetoelectric functionality [1].

[1] M. Giraldo, Q.N. Meier, A. Bortis et al. Magnetoelectric coupling of domains, domain walls and vortices in a multiferroic with independent magnetic and electric order. Nat Commun 12, 3093 (2021).