Geometric frustration on the trillium lattice in a magnetic metal-organic framework
Geometric frustration on the trillium lattice in a magnetic metal-organic framework
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磁性金属有机框架中延龄晶格的几何挫败
DOI：
10.1107/s0108767321093685
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Bulled J
中科院分区：
文献类型：
--
作者：
Bulled J
几何受挫磁体具有重要意义，因为它们的宏观基态简并性会产生许多奇异效应[1]。尽管有大量可能的网络满足这一局部约束，但该领域的大部分内容都集中在陶瓷材料中常见的几种结构类型，例如烧绿石、戈薇等。因此，对更奇特的晶格的挫败研究可能会发现新的磁性相及其相应的物理特性[2]。在致密的金属有机框架Na [Mn (HCOO) 3]中，Mn2+离子(S= 5/2)占据了“延龄”网络的节点。我们表明，这种材料表现出多种几何挫败行为特征：尼尔跃迁被抑制到远低于特征磁相互作用强度[图1c]；中子散射表明短程磁序持续远高于尼尔温度[图1d]；磁化率在 1/3 饱和磁化强度处表现出伪平台。我们证明了一个简单的最近邻海森堡反铁磁体模型定量地解释了每个观测结果，因此 Na [Mn (HCOO) 3] 是该模型在延龄网上的第一个实验实现。我们演示了两者如何将经典自旋液体体系内的几何挫败与低场下的强磁热响应联系起来。
Geometrically-frustrated magnets are of fundamental interest because their macroscopic ground state degeneracies give rise to a number of exotic effects [1]. Despite the large number of possible nets satisfying this local constraint, much of the field has focused on a few structure types common amongst ceramic materials eg, pyrochlore, kagome etc. The study of frustration on more exotic lattices may therefore allow for the discovery of novel magnetic phases and their corresponding physics [2].In the dense metal-organic framework Na [Mn (HCOO) 3], Mn2+ ions (S= 5/2) occupy the nodes of a ‘trillium’net. We show that this material exhibits a variety of behaviour characteristic of geometric frustration: the Néel transition is suppressed well below the characteristic magnetic interaction strength [Figure 1c]; neutron scattering indicates that short-range magnetic order persists far above the Néel temperature [Figure 1d]; and the magnetic susceptibility exhibits a pseudo-plateau at 1/3-saturation magnetisation. We demonstrate that a simple nearest-neighbour Heisenberg antiferromagnet model accounts quantitatively for each observation, and hence Na [Mn (HCOO) 3] is the first experimental realisation of this model on the trillium net. We demonstrate how both link geometric frustration within the classical spin liquid regime to a strong magnetocaloric response at low fields.