Magnetic structure and magnetic properties of synthetic lindgrenite, Cu3(OH)2(MoO4)2.
Magnetic structure and magnetic properties of synthetic lindgrenite, Cu3(OH)2(MoO4)2.
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DOI：
10.1002/chin.200715009
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发表时间：
2006-12
影响因子：
4.6
通讯作者：
S. Vilminot;G. André;M. Richard-Plouet;F. Bourée-Vigneron;M. Kurmoo
中科院分区：
文献类型：
--
作者：
S. Vilminot;G. André;M. Richard-Plouet;F. Bourée-Vigneron;M. Kurmoo
合成Cu 3（OH）2（MoO 4）2由Cu 3（OH）2水镁石带组成，水镁石带由MoO 4连接成3D网络，如矿物林菱镁矿，在1.5和300 K之间的所有温度下。每个带状物由两种不同类型的铜原子（Cu（1）和2Cu（2））之间通过μ 3-OH的三角形连接组成。MoO 4作为单原子桥和三原子桥连接属于三个相邻带的六个Cu原子。磁性与亚铁磁链一致，在13 K下，每个链的磁矩平行于长程磁序。Cu的居里常数为0.468（1）emu K mol-1，韦斯温度为-14.2（2）K，在2K和50 kOe下的饱和磁化强度为0.41 N muB mol-1。中子粉末衍射分析揭示了有序的磁性状态，其中Cu（1）的矩与两个Cu（2）的矩反平行;它们都沿着a轴指向，没有任何几何挫折的迹象。由于Cu原子的三角形拓扑结构（s = 1/2）而可能存在的任何简并性似乎通过从三角形的理想等边几何形状的变形而被解除。的熵，估计从热容测量，达到50%的总的17.7 J K-1 mol-1，接近预期的三个铜原子（3R ln 2），到长程有序温度，和其余的是与低维的材料。
Synthetic Cu3(OH)2(MoO4)2 consists of Cu3(OH)2 brucite ribbons of edge-sharing copper octahedra connected by MoO4 into a 3D network as in the mineral, lindgrenite, for all temperatures between 1.5 and 300 K. Each ribbon consists of a triangular connection between two different types of copper atom (Cu(1) and 2 Cu(2)) via mu3-OH. The MoO4 acts both as one- and three-atom bridges to connect six Cu atoms belonging to three adjacent ribbons. The magnetic properties are consistent with those of ferrimagnetic chains, and the resulting moment of each chain is parallel below the long-range magnetic ordering at 13 K. The Curie constant is 0.468(1) emu K mol-1 of Cu; the Weiss temperature is -14.2(2) K, and the saturation magnetization at 2 K in 50 kOe is 0.41 N muB mol-1 of Cu. Analyses of the neutron powder diffraction reveal an ordered magnetic state where the moment of Cu(1) is antiparallel to those of the two Cu(2); all of them point along the a axis without any sign of geometrical frustration. Any degeneracy that may be present because of the triangular topology of the Cu atoms (s = 1/2) appears to be lifted by the distortion from an ideal equilateral geometry of the triangle. The entropy, estimated from the heat capacity measurements, attains 50% of the total of 17.7 J K-1 mol-1, close to that expected for three Cu atoms (3R ln 2), up to the long range ordering temperature, and the remaining is associated with the low dimensionality of the material.