Reduced crystal symmetry as the origin of the ferroelectric polarization within the incommensurate magnetic phase of TbMn2O5

Article

关键词: MULTIFERROIC COMPOUNDS;    ELECTRIC POLARIZATION;    NEUTRON-DIFFRACTION;    RMN2O5 R;    TRANSITIONS;    DYMN2O5;    YMN2O5;    ORDER;   

DOI  :  10.1103/PhysRevB.105.214413

来源: SCIE

【 摘 要 】

The precise crystal symmetry, and hence the emergence of the electric polarization, still remains an open question in the multiferroic RMn2O5 (R = rare earth, Bi, Y). While previous diffraction studies have indicated the centrosymmetric space group Pbam, an atomic displacement allowing for electric polarization would require a noncentrosymmetric crystal symmetry. Our single crystal neutron diffraction experiments on TbMn2O5 provide direct evidence of a reduced crystallographic symmetry with the polar space group P1211 already above the multiferroic phase transition, indicating that a symmetric Si middot Sj spin coupling, i.e. magnetostriction is the dominating mechanism in the commensurate magnetic phase. Furthermore, the commensurate magnetic reflections are in accordance with a quartile step spin spiral along the c axis. Therefore, the antisymmetric Si x Sj exchange via the inverse Dzyaloshinskii-Moriya interaction contributes as well and becomes the leading term in the low-temperature incommensurate spin-spiral magnetic phase. These findings provide important information for the understanding of the complex interplay between magnetic and structural order throughout the multiferroic RMn2O5 series.

【 授权许可】

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