酸化希土類マンガン(III、IV)の強誘電性-反強磁性同時相転移

我们对一系列分子式为RMn_2O_5的锰氧化物进行了介电、磁性和磁电性能的研究，其中R为Eu和Yb、Y或Bi之间的稀土元素。除了Mn自旋和稀土自旋在较低温度下的螺旋磁有序的发展外，我们还获得了连续结构转变的证据，这些晶体调谐成铁电体。认为自发极化的起因是三种不同的金属离子Mn^3+、Mn^4+和R^3+的位移。低磁跃迁（R^<3+>级自旋）通常伴随着自发跃迁变化较大的结构跃迁。

We performed dielectric, magnetic, and magnetoelectric studies of a series of manganites with a formula of RMn_2O_5, where R is a rare earth between Eu and Yb, Y or Bi. In addition to the development of helimagnetic ordering of Mn spins and that of rare earth spins at lower temperature, we obtained the evidences of successive structural transitions, where these crystals tuned into ferroelectric. The origin of the spontaneous polarization was considered to be the displacements of three different kind of metallic ions Mn^3+'s, Mn^<4+>'s and R^<3+>'s. The lower magnetic transition, where the spins of R^<3+> order is generally accompanied with a structural transition with a large change in spontaneous transition.