Site Specific X-ray Anomalous Dispersion of the Geometrically Frustrated Kagom Magnet, Herbertsmithite, ZnCu3(OH)6Cl2

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• 作者：Danna E. Freedman ; Tianheng H. Han ; Andrea Prodi ; Peter Mller ; Qing-Zhen Huang ; Yu-Sheng Chen ; Samuel M. Webb ; Young S. Lee ; Tyrel M. McQueen ; Daniel G. Nocera
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：November 17, 2010
• 年：2010
• 卷：132
• 期：45
• 页码：16185-16190
• 全文大小：244K
• 年卷期：v.132,no.45(November 17, 2010)
• ISSN：1520-5126

文摘

Structural characterization, exploiting X-ray scattering differences at elemental absorption edges, is developed to quantitatively determine crystallographic site-specific metal disorder. We apply this technique to the problem of Zn−Cu chemical disorder in ZnCu₃(OH)₆Cl₂. This geometrically frustrated kagom antiferromagnet is one of the best candidates for a spin-liquid ground state, but chemical disorder has been suggested as a mundane explanation for its magnetic properties. Using anomalous scattering at the Zn and Cu edges, we determine that there is no Zn occupation of the intralayer Cu sites within the kagom layer; however there is Cu present on the Zn intersite, leading to a structural formula of (Zn_0.85Cu_0.15)Cu₃(OH)₆Cl₂. The lack of Zn mixing onto the kagom lattice sites lends support to the idea that the electronic ground state in ZnCu₃(OH)₆Cl₂ and its relatives is nontrivial.