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Title: Ferroelectricity in the Magnetic E-Phase of Orthorhombic Perovskites

Abstract

We show that the symmetry of the spin zigzag chain E phase of the orthorhombic perovskite manganites and nickelates allows for the existence of a finite ferroelectric polarization. The proposed microscopic mechanism is independent of spin-orbit coupling. We predict that the polarization induced by the E-type magnetic order can potentially be enhanced by up to 2 orders of magnitude with respect to that in the spiral magnetic phases of TbMnO3 and similar multiferroic compounds.

Authors:
 [1];  [2];  [1]
  1. ORNL
  2. Florida State University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931863
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 97
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; NICKELATES; MANGANESE OXIDES; PEROVSKITES; ORTHORHOMBIC LATTICES; POLARIZATION; SYMMETRY; FERROELECTRIC MATERIALS; MAGNETIC PROPERTIES

Citation Formats

Sergienko, Ivan A, Sen, Cengiz, and Dagotto, Elbio R. Ferroelectricity in the Magnetic E-Phase of Orthorhombic Perovskites. United States: N. p., 2006. Web. doi:10.1103/PhysRevLett.97.227204.
Sergienko, Ivan A, Sen, Cengiz, & Dagotto, Elbio R. Ferroelectricity in the Magnetic E-Phase of Orthorhombic Perovskites. United States. doi:10.1103/PhysRevLett.97.227204.
Sergienko, Ivan A, Sen, Cengiz, and Dagotto, Elbio R. Sun . "Ferroelectricity in the Magnetic E-Phase of Orthorhombic Perovskites". United States. doi:10.1103/PhysRevLett.97.227204.
@article{osti_931863,
title = {Ferroelectricity in the Magnetic E-Phase of Orthorhombic Perovskites},
author = {Sergienko, Ivan A and Sen, Cengiz and Dagotto, Elbio R},
abstractNote = {We show that the symmetry of the spin zigzag chain E phase of the orthorhombic perovskite manganites and nickelates allows for the existence of a finite ferroelectric polarization. The proposed microscopic mechanism is independent of spin-orbit coupling. We predict that the polarization induced by the E-type magnetic order can potentially be enhanced by up to 2 orders of magnitude with respect to that in the spiral magnetic phases of TbMnO3 and similar multiferroic compounds.},
doi = {10.1103/PhysRevLett.97.227204},
journal = {Physical Review Letters},
number = ,
volume = 97,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Recently, a magnetically induced ferroelectricity occurring at magnetic domain wall of double perovskite Lu{sub 2}CoMnO{sub 6} has been reported experimentally. However, there exists a conflict whether the electric polarization is along b or c direction. Here, by first-principles calculations, we show that the magnetic domain wall (with ↑↑↓↓ spin configuration) can lead to the ferroelectric displacements of R{sup 3+}, Ni{sup 2+}, Mn{sup 4+}, and O{sup 2−} ions in double perovskites R{sub 2}NiMnO{sub 6} (R = rare earth ion) via exchange striction. The resulted electric polarization is along b direction with the P2{sub 1} symmetry. We further reveal the origin of the ferroelectricmore » displacements as that: (1) on a structural point of view, such displacements make the two out-of-plane Ni-O-Mn bond angles as well as Ni-Mn distance unequal, and (2) on an energy point of view, such displacements weaken the out-of-plane Ni-Mn super-exchange interaction obviously. Finally, our calculations show that such a kind of ferroelectric order is general in ferromagnetic double perovskites.« less
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  • Two microscopic mechanisms helping us to understand the multiferroic behavior of distorted rare-earth manganites are here briefly reviewed. The original work was carried out by means of Hamiltonian modeling and first-principles density functional simulations. Our first topic concerns the link between the Dzyaloshinskii Moriya interaction and ferroelectricity in incommensurate magnets. We argue that the Dzyaloshinskii Moriya interaction may play a key role since (i) it induces ferroelectric displacements of oxygen atoms and (ii) it favors the stabilization of a helical magnetic structure at low temperatures. Our second topic concerns the prediction, based on Landau theory, that the symmetry of themore » zigzag spin chains in the AFM-E (E-type antiferromagnetic) orthorhombic manganites (such as HoMnO3) allows a finite polarization along the c axis. The microscopic mechanism at the basis of ferroelectricity is interpreted through a gain in band energy of the eg electrons within the orbitally degenerate double-exchange model. Related Monte Carlo simulations have confirmed that the polarization can be much higher than what is observed in spiral magnetic phases. Density functional calculations performed on orthorhombic HoMnO3 quantitatively confirm a magnetically induced ferroelectric polarization up to 6 C cm 2, the largest reported so far for improper magnetic ferroelectrics. We find in HoMnO3, in addition to the conventional displacement mechanism, a sizable contribution arising from the purely electronic effect of orbital polarization. The relatively large ferroelectric polarization, present even with centrosymmetric atomic positions, is a clear sign of a magnetism-induced electronic mechanism at play, which is also confirmed by the large displacements of the Wannier function centers with respect to the corresponding ions in AFM-E HoMnO3. The final polarization is shown to be the result of competing effects, as shown by the opposite signs of the eg and t2g contributions to the ferroelectric polarization.« less
  • No abstract prepared.