Origin of the multiferroic spiral spin-order in the RMnO3 perovskites

Abstract

The origin of the spiral spin-order in perovskite multiferroic manganites $R$MnO${}_3$ ($RE=$ Tb or Dy) is here investigated using a two $e_{\mathrm{g}}$-orbitals double-exchange model. Our main result is that the experimentally observed spiral phase can be stabilized by introducing a relatively weak next-nearest-neighbor superexchange coupling ($\sim 10$ of the nearest-neighbor superexchange). Moreover, the Jahn-Teller lattice distortion is also shown to be essential to obtain a realistic spiral period. Supporting our conclusions, the generic phase diagram of undoped perovskite manganites is obtained using Monte Carlo simulations, showing phase transitions from the A-type antiferromagnet, to the spiral phase, and finally to the E-type antiferromagnet, with decreasing size of the $R$ ions. These results are qualitatively explained by the enhanced relative intensity of the superexchanges.

6 pages, 4 figures

References in corpus (4)

• Spin current and magneto-electric effect in non-collinear magnets
• Role of the Dzyaloshinskii-Moriya interaction in multiferroic perovskites
• Magnetically driven ferroelectric order in Ni${}_3$V${}_2$O${}_8$
• Spin-Orbit Coupling and Ion Displacements in Multiferroic TbMnO3