Ferroelectric phase transitions of 3d -spin origin in Eu1-x Yx Mn O3
Ferroelectric phase transitions of 3d -spin origin in Eu1-x Yx Mn O3
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DOI：
10.1103/physrevb.76.184418
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发表时间：
2007-11
影响因子：
3.7
通讯作者：
Y. Yamasaki;S. Miyasaka;T. Gotō;H. Sagayama;T. Arima;Y. Tokura
中科院分区：
文献类型：
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作者：
Y. Yamasaki;S. Miyasaka;T. Gotō;H. Sagayama;T. Arima;Y. Tokura
钙钛矿型稀土锰氧化物(和Dy)在经历铁电相变的同时，还发生了MnSpin的共线到非共线的磁相变，其中的电极化方向可以由外磁场控制。为了阐明MnSpins的磁性转变与铁电转变之间的关系，我们研究了一个没有稀土离子磁矩的钙钛矿型混晶系统。本系统的选择使我们能够系统地研究介电、磁性(来自Mn自旋的)和超晶格性质之间的关联，同时改变钙钛矿晶格扭曲或等效地竞争的Mn自旋超交换相互作用。含有和0.4的化合物发生了铁电相变，自发极化沿轴向，这与调制矢量沿轴向形成a平面摆线自旋结构有关。其中，发现复合材料经历了从轴向轴的极化翻转，这不仅是由于热诱导的，而且是由沿轴向施加的磁场引起的。磁场激发极化翻转及其机制可以用摆线自旋平面从由Mn自旋翻转到自旋翻转来完全解释。这与与磁自旋耦合的稀有稀土伊辛矩的情况形成了鲜明的对比，在这种情况下，沿着轴和轴的磁场，而不是沿着轴(直到)的磁场，可以将极化从轴向轴反转到轴。
Perovskite-type rare-earth manganites(and Dy) undergo the ferroelectric transitions concomitantly with the collinear to noncollinear magnetic transitions of Mnspins, in which the electric polarization direction can be controlled by an external magnetic field. To clarify how the magnetic transition of Mnspins is correlated with the ferroelectric transition, we have investigated a mixed-crystal system of perovskite-typewithout themagnetic moments of the rare earth ions. The choice of the present system has enabled us to systematically investigate the correlation between dielectric, magnetic (of Mn spin origin), and superlattice properties with varying the perovskite lattice distortion or equivalently the competing Mn spin superexchange interactions. The compounds withand 0.4 undergo the ferroelectric transitions with the spontaneous polarization along theaxis, which is associated with the formation of a-plane cycloidal spin structure with the modulation vector along theaxis. Among them, thecompound was found to undergo the polarization flop from along theaxis to theaxis as induced not only thermally but also by a magnetic field applied along theaxis. The magnetic-field induced polarization flop and its mechanism forcan be fully accounted for in terms of the rotation of the cycloidal spin plane fromtostemming from the Mn spin flops. This is contrasted by the case ofandwith the rare-earthIsing moments coupled to the Mnspins, in which magnetic fields along theaxis and theaxis, but not along theaxis (up to), can flop the polarization from along theaxis to theaxis.