Magnetically-induced ferroelectricity in the (ND4)2[FeCl5(D2O)] molecular compound.
Magnetically-induced ferroelectricity in the (ND4)2[FeCl5(D2O)] molecular compound.
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DOI：
10.1038/srep14475
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发表时间：
2015-09-29
影响因子：
4.6
通讯作者：
Chapon L
中科院分区：
文献类型：
--
作者：
Alberto Rodríguez-Velamazán J;Fabelo Ó;Millán Á;Campo J;Johnson RD;Chapon L
迄今为止报道的磁电多铁性材料的数量很少，因为破坏反转对称性并引起不适当的铁电极化的磁性结构通常通过不同磁性相互作用之间的微妙竞争而产生。（NH 4）2[FeCl 5（H2O）]化合物是在分子材料中观察到这种不适当的铁电性的罕见情况。我们已经使用单晶和粉末中子衍射获得详细的解决方案的晶体和磁性结构的（NH 4）2[FeCl 5（H 2 O）]，从我们确定的机制，多铁性。从晶体结构分析，我们观察到一个有序-无序相变有关的铵抗衡有序。我们已经确定的磁性结构低于TN，在2 K和零磁场，这对应于摆线自旋安排的磁矩包含在ac平面，平行于c轴传播。观察到的铁电性可以解释，从获得的磁结构，通过逆Dzyaloshinskiii-Moriya机制。
The number of magnetoelectric multiferroic materials reported to date is scarce, as magnetic structures that break inversion symmetry and induce an improper ferroelectric polarization typically arise through subtle competition between different magnetic interactions. The (NH4)2[FeCl5(H2O)] compound is a rare case where such improper ferroelectricity has been observed in a molecular material. We have used single crystal and powder neutron diffraction to obtain detailed solutions for the crystal and magnetic structures of (NH4)2[FeCl5(H2O)], from which we determined the mechanism of multiferroicity. From the crystal structure analysis, we observed an order-disorder phase transition related to the ordering of the ammonium counterion. We have determined the magnetic structure below TN, at 2 K and zero magnetic field, which corresponds to a cycloidal spin arrangement with magnetic moments contained in the ac-plane, propagating parallel to the c-axis. The observed ferroelectricity can be explained, from the obtained magnetic structure, via the inverse Dzyaloshinskii-Moriya mechanism.