Berlin 2012 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 4: Multiferroics II (jointly with MA, DS, KR, TT)

DF 4.2: Talk

Monday, March 26, 2012, 15:30–15:45, EB 301

Structures and energetics of domain walls in polar hexagonal manganites — •Yu Kumagai and Nicola Spaldin — Department of Materials, ETH Zurich

We use first-principles density functional calculations to study the domain walls in the multiferroic hexagonal manganites, h-RMnO₃ (R=Sc, Y, Dy–Lu). These materials show an improper ferroelectricity induced by structural trimerization, resulting in 2×3=6 domains (2 for ferroelectricity and 3 for trimerization origin) below the Curie temperature with an intriguing cloverleaf pattern of domains [1,2]. Our calculations explain the observation that ferroelectric (FE) domain walls exist only in combination with antiphase DWs. We find that interlocked ferroelectric and antiphase domain walls have lower energies than typical FE domain walls in conventional ferroelectrics, as well as a much narrower wall width; both factors result from the layered geometry of the h-RMnO₃ structure.

[1] T. Choi et al., Nature Mater. 9, 253 (2010).

[2] T. Jungk et al., Appl. Phys. Lett. 97, 012904 (2010).