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arXiv · 1109.1448

Observation of persistent centrosymmetricity in the hexagonal manganite family

Yu Kumagai·Alexei A. Belik·Martin Lilienblum·Naëmi Leo·Manfred Fiebig·Nicola A. Spaldin
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Abstract

The controversy regarding the ferroelectric behavior of hexagonal InMnO$_3$ is resolved by using a combination of x-ray diffraction (XRD), piezoresponse force microscopy (PFM), second harmonic generation (SHG), and density functional theory (DFT). While XRD data show a symmetry-lowering unit-cell tripling, which is also found in the multiferroic hexagonal manganites of $P6_3cm$ symmetry, PFM and SHG do not detect ferroelectricity at ambient or low temperature, in striking contrast to the behavior in the multiferroic counterparts. We propose instead a centrosymmetric $P\bar{3}c$ phase as the ground state structure. Our DFT calculations reveal that the relative energy of the ferroelectric and nonferroelectric structures is determined by a competition between electrostatics and oxygen-$R$-site covalency, with an absence of covalency favoring the ferroelectric phase.

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Yu Kumagai, Alexei A. Belik, Martin Lilienblum, Naëmi Leo, Manfred Fiebig, Nicola A. Spaldin. 2011-09-07. Observation of persistent centrosymmetricity in the hexagonal manganite family. https://doi.org/10.1103/physrevb.85.174422

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