Microscopic model and phase diagrams of the multiferroic perovskite manganites

Article

关键词: NEUTRON-DIFFRACTION;    MAGNETIC-PROPERTIES;    WEAK FERROMAGNETISM;    DISTORTION;    FEATURES;    ELECTROMAGNONS;    POLARIZATION;    TRANSITION;    EVOLUTION;    PR;   

DOI  :  10.1103/PhysRevB.80.134416

来源: SCIE

【 摘 要 】

Orthorhombically distorted perovskite manganites, RMnO3 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 RMnO3 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 parallel to a and the bc-plane spin cycloid with P parallel to 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.

【 授权许可】

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