Noncubic crystallographic symmetry of a cubic ferromagnet: Simultaneous structural change at the ferromagnetic transition
Noncubic crystallographic symmetry of a cubic ferromagnet: Simultaneous structural change at the ferromagnetic transition
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立方铁磁体的非立方晶体对称性：铁磁转变时的同时结构变化
DOI：
10.1103/physrevb.77.014407
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发表时间：
2008-01
影响因子：
3.7
通讯作者：
中科院分区：
文献类型：
--
作者：
在过去的几十年中，传统的衍射法已经揭示了铁磁转变，磁矩的排序，一般不涉及晶体结构的变化;因此，立方顺磁体被认为是铁磁转变后转变为立方铁磁体。然而，与高分辨率同步辐射X射线衍射仪XRD，我们显示了直接的证据i的非立方对称性的典型立方铁磁体CoFe 2 O 4，T b0.3Dy0.7Fe2 Terfenol-D，和DyCo 2和ii的同时在铁磁转变温度TC的DyCo 2的结构变化。这些结果表明，铁磁转变也是一种结构转变，产生符合自发磁化MS方向的低晶体对称性。原位XRD观察进一步揭示了磁畴的转变也是非立方晶畴的转变，与铁电畴转变的方式相同。通过基于磁弹性耦合的唯象方法，我们从理论上证明了铁磁相变后的结构变化是所有立方铁磁体的普遍效应。我们的工作为铁磁体中的磁致伸缩和铁电体中的电应变效应提供了一个简单而统一的介观解释。它还可以为开发高磁响应材料提供见解。
Conventional diffractometry over the past decades has revealed that the ferromagnetic transition, an ordering of the magnetic moment, involves no crystal structure change in general; thus a cubic paramagnet has been considered to transform into a cubic ferromagnet upon a ferromagnetic transition. However, with highresolution synchrotron x-ray diffractometry XRD, we show direct evidence for i the noncubic symmetry of typical cubic ferromagnets CoFe2O4 ,T b0.3Dy0.7Fe2 Terfenol-D, and DyCo2 and ii a simultaneous structural change at ferromagnetic transition temperature TC in DyCo2. These results suggest that ferromagnetic transition is also a structural transition, yielding a low crystallographic symmetry that conforms to the spontaneous magnetization MS direction. In situ XRD observation further revealed that the switching of magnetic domains is also a switching of the noncubic crystallographic domains, in the same way as the ferroelectric domain switching. By a phenomenological approach based on magnetoelastic coupling, we proved theoretically that structure change upon a ferromagnetic transition is a general effect for all cubic ferromagnets. Our work leads to a simple and unified mesoscopic explanation for both magnetostriction in ferromagnets and electrostrain effect in ferroelectrics. It may also provide insight for developing highly magnetoresponsive materials.
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影响因子：
3.7
作者：
BERGMAN, DJ;HALPERIN, BI
通讯作者：
HALPERIN, BI
影响因子：
64.8
作者：
Tegus, O;Brück, E;de Boer, FR
通讯作者：
de Boer, FR
影响因子：
1.6
作者：
R. Ahluwalia;T. Lookman;A. Saxena;S. R. Shenoy
通讯作者：
R. Ahluwalia;T. Lookman;A. Saxena;S. R. Shenoy
影响因子：
--
作者：
L. W. Mckeehan
通讯作者：
L. W. Mckeehan
影响因子：
8.6
作者：
Guo, R;Cross, LE;Shirane, G
通讯作者：
Shirane, G