Department of Physics and Center for Materials Innovation, Washington University in St Louis, 1 Brookings Drive, St Louis, MO 63130, USA.
J Phys Condens Matter. 2010 Aug 25;22(33):334211. doi: 10.1088/0953-8984/22/33/334211. Epub 2010 Aug 4.
We have investigated the structural and magnetic properties of two classes of spin S = 1/2 antiferromagnetic quasi-triangular lattice materials: Cu(2(1-x))Zn(2x)(OH)(3)NO(3) (0 ≤ x ≤ 0.65) and its long chain organic derivatives Cu(2(1-x))Zn(2x)(OH)(3)(C(7)H(15)COO)·mH(2)O (0 ≤ x ≤ 0.29). The series of layered structure compounds constitute a substitutional magnetic system, in which spin S = 1/2Cu(2+) ions and nonmagnetic Zn(2+) ions are arranged on a two-dimensional quasi-triangular lattice. For the nitrate compounds we found that the substitution of Zn(2+) ions can continuously decrease the Néel temperature, T(N), but never completely remove the magnetic order. In addition, the frustration effect in these materials is suppressed by a three-dimensional interlayer interaction. On the other hand, the corresponding long chain alkyl carboxylic acid group of intercalated materials, Cu(2(1-x))Zn(2x)(OH)(3)(C(7)H(15)COO)·mH(2)O, show spin-glass-like behavior, which is caused by the interplay of geometric frustration and mixed sign interactions. A tentative explanation for these findings is proposed in terms of a cluster-glass picture.
我们研究了两类自旋 S = 1/2 反铁磁准三角晶格材料的结构和磁性：Cu(2(1-x))Zn(2x)(OH)(3)NO(3)（0 ≤ x ≤ 0.65）及其长链有机衍生物 Cu(2(1-x))Zn(2x)(OH)(3)(C(7)H(15)COO)·mH(2)O（0 ≤ x ≤ 0.29）。这一系列层状结构化合物构成了取代磁体系统，其中自旋 S = 1/2Cu(2+)离子和非磁性 Zn(2+)离子排列在二维准三角晶格上。对于硝酸盐化合物，我们发现 Zn(2+)离子的取代可以连续降低奈尔温度 T(N)，但永远不会完全消除磁有序。此外，这些材料中的挫折效应被层间三维相互作用抑制。另一方面，插层材料的相应长链烷基羧酸根 Cu(2(1-x))Zn(2x)(OH)(3)(C(7)H(15)COO)·mH(2)O 表现出类似玻璃的自旋行为，这是由几何挫折和混合符号相互作用的相互作用引起的。基于团簇玻璃的图像提出了对这些发现的一个初步解释。
