Microscopic model and phase diagrams of the multiferroic perovskite manganites

Masahito Mochizuki, Nobuo Furukawa

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Abstract

Orthorhombically distorted perovskite manganites, RMn O3 with R being a trivalent rare-earth ion, exhibit a variety of magnetic and electric phases including multiferroic (i.e., concurrently magnetic and ferroelectric) phases and fascinating magnetoelectric phenomena. We theoretically study the phase diagram of RMn O3 by constructing a microscopic spin model, which includes not only the superexchange interaction but also the single-ion anisotropy (SIA) and the Dzyaloshinsky-Moriya interaction (DMI). Analysis of this model using the Monte Carlo method reproduces the experimental phase diagrams as functions of the R -ion radius, which contain two different multiferroic states, i.e., the ab -plane spin cycloid with ferroelectric polarization P□a and the bc -plane spin cycloid with P□c. The orthorhombic lattice distortion or the second-neighbor spin exchanges enhanced by this distortion exquisitely controls the keen competition between these two phases through tuning the SIA and DMI energies. This leads to a lattice-distortion-induced reorientation of P from a to c in agreement with the experiments. We also discuss spin structures in the A -type antiferromagnetic state, those in the cycloidal spin states, origin and nature of the sinusoidal collinear spin state, and many other issues.

Original languageEnglish
Article number134416
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume80
Issue number13
DOIs
Publication statusPublished - 2009 Oct 19

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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