Mechanism of Ferroelectricity in Half-Doped Manganites with Pseudocubic and Bilayer Structure

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概要

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• By means of density-functional simulations for half-doped manganites, such as pseudocubic Pr<inf>0.5</inf>Ca<inf>0.5</inf>MnO<inf>3</inf>and bilayer PrCa<inf>2</inf>Mn<inf>2</inf>O<inf>7</inf>, we discuss the occurrence of ferroelectricity and we explore its crucial relation to the crystal structure and to peculiar charge/spin/orbital ordering effects. In pseudocubic Pr<inf>0.5</inf>Ca<inf>0.5</inf>MnO<inf>3</inf>, ferroelectricity is induced in the Zener polaron type structure, where Mn ions are dimerized. In marked contrast, in bilayer PrCa<inf>2</inf>Mn<inf>2</inf>O<inf>7</inf>, it is the displacement of apical oxygens bonded to either Mn³⁺or Mn⁴⁺ions that plays a key role in the rising of ferroelectricity. Importantly, local dipoles due to apical oxygens are also intimately linked to charge and orbital ordering patterns in MnO<inf>2</inf>planes, which in turn contribute to polarization. Finally, an important outcome of our work consists in proposing Born effective charges as a valid mean to quantify charge disproportionation effects, in terms of anisotropy and size of electronic clouds around Mn ions.

• 2013-11-15

著者

• Yamauchi Kunihiko

  ISIR-SANKEN, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

• Picozzi Silvia

  Consiglio Nazionale delle Ricerche---Institute for Superconducting and Innovative Materials and Devices (CNR-SPIN), 67100 L'Aquila, Italy

関連論文

• Ab initio Investigations of Fe2+/Fe3+ Bond Dimerization and Ferroelectricity Induced by Intermediate Site/Bond-Centered Charge Ordering in Magnetite
• Bandstructure and Fermi Surfaces of CeRh3B2
• Mechanism of Ferroelectricity in Half-Doped Manganites with Pseudocubic and Bilayer Structure
• Mechanism of Ferroelectricity in Half-Doped Manganites with Pseudocubic and Bilayer Structure

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