Issue Eur. Phys. J. B Volume 71, Number 3, October I 2009 Magnetoelectric Interaction Phenomena in Crystals Page(s) 339 - 344 Section Topical issue on Magnetoelectric Interaction Phenomena in Crystals DOI 10.1140/epjb/e2009-00225-1

Eur. Phys. J. B 71, 339-344 (2009)
DOI: 10.1140/epjb/e2009-00225-1

Double-exchange model study of multiferroic RMnO₃ perovskites

S. Dong^{1, 2, 3}, R. Yu^{1, 2}, S. Yunoki^{4, 5}, J.-M. Liu^{3, 6} and E. Dagotto<sup>1, 2

1</sup>  Department of Physics and Astronomy, University of Tennessee, Knoxville, 37996 TN, USA
²  Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, 32831 TN, USA
³  Nanjing National Laboratory of Microstructures, Nanjing University, 210093 Nanjing, P.R. China
⁴  Computational Condensed Matter Physics Laboratory, RIKEN, Wako, 351-0198 Saitama, Japan
⁵  CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama, 332-0012, Japan
⁶  International Center for Materials Physics, Chinese Academy of Sciences, 110016 Shenyang, P.R. China

saintdosnju@gmail.com

Received 27 February 2009 / Received in final form 26 March 2009 / Published online 15 July 2009

Abstract
In this proceeding, recent theoretical investigations by the authors on the multiferroic RMnO₃ perovskites are briefly reviewed at first. Using the double-exchange model, the realistic spiral spin order in undoped manganites such as TbMnO₃ and DyMnO₃ is well reproduced by incorporating a weak next-nearest neighbor superexchange (~10% of nearest neighbor superexchange) and moderate Jahn-Teller distortion. The phase transitions from the A-type antiferromagnet (as in LaMnO₃), to the spiral phase (as in TbMnO₃), and finally to the E-type antiferromagnet (as in HoMnO₃), with decreasing size of the R ions, were also explained. Moreover, new results of phase diagram of the three-dimensional lattice are also included. The ferromagnetic tendency recently discovered in the LaMnO₃ and TbMnO₃ thin films is explained by considering the substrate stress. Finally, the relationship between our double-exchange model and a previously used J₁-J₂-J₃ model is further discussed from the perspective of spin wave excitations.

PACS
75.80.+q - Magnetomechanical and magnetoelectric effects, magnetostriction.
75.47.Lx - Manganites.
75.30.Kz - Magnetic phase boundaries.
75.30.Ds - Spin waves.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2009

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