Unconventional order-disorder phase transition in improper ferroelectric hexagonal manganites

Abstract

The improper ferroelectricity in YMnO${}_3$ and other related multiferroic hexagonal manganites are known to cause topologically protected ferroelectric domains that give rise to rich and diverse physical phenomena. The local structure and structural coherence across the ferroelectric transition, however, were previously not well understood. Here we reveal the evolution of the local structure with temperature in YMnO${}_3$ using neutron total scattering techniques, and interpret them with the help of first-principles calculations. The results show that, at room temperature, the local and average structures are consistent with the established ferroelectric $P{6}_{3}cm$ symmetry. On heating, both local and average structural analyses show striking anomalies from $\sim 800$ K up to the Curie temperature consistent with increasing fluctuations of the order parameter angle. These fluctuations result in an unusual local symmetry lowering into a \textit{continuum of structures} on heating. This local symmetry breaking persists into the high-symmetry non-polar phase, constituting an unconventional type of order-disorder transition.

arXiv comment10 pages, 5 figures

References in corpus (22)

• Polarization rotation via a monoclinic phase in the piezoelectric 92%PbZn1/3Nb2/3O3-8%PbTiO3
• Anisotropic conductance at improper ferroelectric domain walls
• The ferroelectric transition in YMnO${}_3$ from first principles
• The High Temperature Phase Transitions of Hexagonal YMnO3
• Landau theory of topological defects in multiferroic hexagonal manganites
• From multiferroics to cosmology: Scaling behaviour and beyond in the hexagonal manganites
• Orbital correlations in the pseudo-cubic \emph{O} and rhombohedral $R$-phases of LaMnO${}_3$
• Topological defects as relics of emergent continuous symmetry and Higgs condensation of disorder in ferroelectrics
• Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions
• Electrostatic topology of ferroelectric domains in YMnO${}_3$
• Collective magnetism at multiferroic vortex domain walls
• Observation of persistent centrosymmetricity in the hexagonal manganite family
• Goldstone-Mode Phonon Dynamics in the Pyrochlore Cd2Re2O7
• Experimental evidence for an intermediate phase in the multiferroic YMnO3
• Global formation of topological defects in the multiferroic hexagonal manganites
• Improper ferroelectricity and multiferroism in 2HBaMnO${}_3$
• Hidden order in hexagonal RMnO3 multiferroics
• Reconciliation of local and long range tilt correlations in underdoped La2-xBaxCuO4
• Goldstone-like phonon modes in a (111)-strained perovskite
• Studies on the high-temperature ferroelectric transition of multiferroic hexagonal manganite RMnO3
• Measurements and ab initio Molecular Dynamics Simulations of the High Temperature Ferroelectric Transition in Hexagonal RMnO3
• Unusual ferroelectric and magnetic phases in multiferroic 2H-BaMnO${}_3$ ceramics

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• Manifestion of structural Higgs and Goldstone modes in the hexagonal manganites
• Local atomic and magnetic structure of multiferroic (Sr,Ba)(Mn,Ti)O${}_3$
• Local structure and its implications for the relaxor ferroelectric Cd${}_2$Nb${}_2$O${}_7$
• Relaxation Critical Dynamics with Emergent Symmetry
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