Asymmetric Character of the Ferroelectric Phase Transition and Charged Domain Walls in a Hybrid Improper Ferroelectric
Abstract
In improper ferroelectrics, the spontaneous ordering is typically driven by a structural distortion or a magnetic spin alignment. The induced electric polarization is only a secondary effect. This dependence is a rich source for unusual phenomena and ferroelectric domain configurations for proper, polarization-driven ferroelectrics. This study focuses on the polar domain structure and the hysteretic behavior at the ferroelectric phase transition in Ca3Mn1.9Ti0.1O7 as a representative of the recently discovered hybrid improper ferroelectric class of multiferroics. Combining optical second harmonic generation and Raman spectroscopy gives access to the spontaneous structural distortion and the resulting improper electric polarization. This study shows that hybrid improper ferroelectrics contrast proper and improper ferroelectrics in several ways. Most intriguingly, adjacent ferroelectric domains favor head-to-head and tail-to-tail domain walls over charge-neutral configurations. Furthermore, the phase transition occurs in an asymmetric fashion. The regime of phase coexistence of the nonpolar and polar phases shows a clear and abrupt upper temperature limit. In contrast, the coexistence toward low temperatures is best described as a fade-out process, where 100-nm-sized islands of the nonpolar phase expand deep into the polar phase. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000505453Publication status
publishedExternal links
Journal / series
Advanced Electronic MaterialsVolume
Pages / Article No.
Publisher
Wiley-VCHSubject
charged domain walls; hybrid improper ferroelectric; multiferroic; phase transitionOrganisational unit
03918 - Fiebig, Manfred / Fiebig, Manfred
09778 - Simonov, Arkadiy / Simonov, Arkadiy
Funding
188414 - Multifunctional oxide electronics using natural ferroelectric superlattices (SNF)
178825 - Dynamical processes in systems with strong electronic correlations (SNF)
694955 - In-situ second harmonic generation for emergent electronics in transition-metal oxides (EC)
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