Site specific X-ray anomalous dispersion of the geometrically frustrated kagomé magnet, herbertsmithite, ZnCu(3)(OH)(6)Cl(2).
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 ZnCu(3)(OH)(6)Cl(2). This geometrically frustrated kagomé 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 kagomé layer; however there is Cu present on the Zn intersite, leading to a structural formula of (Zn(0.85)Cu(0.15))Cu(3)(OH)(6)Cl(2). The lack of Zn mixing onto the kagomé lattice sites lends support to the idea that the electronic ground state in ZnCu(3)(OH)(6)Cl(2) and its relatives is nontrivial.
Department of Chemistry, 6-335, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Danna E
DE
Freedman
Tianheng H
TH
Han
Andrea
A
Prodi
Peter
P
Müller
Qing-Zhen
QZ
Huang
Yu-Sheng
YS
Chen
Samuel M
SM
Webb
Young S
YS
Lee
Tyrel M
TM
McQueen
Daniel G
DG
Nocera