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】
Free