Nat Mater. 2012 May 6;11(6):493-6. doi: 10.1038/nmat3329.
The emergence of complex electronic behaviour from simple ingredients has resulted in the discovery of numerous states of matter. Many examples are found in systems exhibiting geometric magnetic frustration, which prevents simultaneous satisfaction of all magnetic interactions. This frustration gives rise to complex magnetic properties such as chiral spin structures, orbitally driven magnetism, spin-ice behaviour exhibiting Dirac strings with magnetic monopoles, valence-bond solids and spin liquids. Here we report the synthesis and characterization of LiZn(2)Mo(3)O(8), a geometrically frustrated antiferromagnet in which the magnetic moments are localized on small transition-metal clusters rather than individual ions. By doing so, first-order Jahn-Teller instabilities and orbital ordering are prevented, allowing the strongly interacting magnetic clusters in LiZn(2)Mo(3)O(8) to probably give rise to an exotic condensed valence-bond ground state reminiscent of the proposed resonating valence-bond state. Our results also link magnetism on clusters to geometric magnetic frustration in extended solids, demonstrating a new approach for unparalleled chemical control and tunability in the search for collective, emergent electronic states of matter.
从简单成分中出现复杂的电子行为导致了多种物质状态的发现。许多例子存在于表现出几何磁阻挫的系统中，这阻止了所有磁相互作用的同时满足。这种阻挫导致了复杂的磁性，如手性自旋结构、轨道驱动的磁性、表现出具有磁单极子的狄拉克弦的自旋冰行为、价带固体和自旋液体。在这里，我们报告了 LiZn(2)Mo(3)O(8)的合成和表征，LiZn(2)Mo(3)O(8)是一种几何磁阻挫的反铁磁体，其中磁矩定域在小的过渡金属簇上，而不是单个离子上。通过这样做，阻止了一级 Jahn-Teller 不稳定性和轨道有序化，使得 LiZn(2)Mo(3)O(8)中强相互作用的磁性簇可能导致一种奇异的凝聚价带基态，类似于所提出的共振价带态。我们的结果还将簇上的磁性与扩展固体中的几何磁阻挫联系起来，展示了一种新的方法，用于在寻找物质的集体、涌现电子态的过程中进行无与伦比的化学控制和可调性。
