Strong magnetic frustration in Y${}_3$Cu${}_9$(OH)${}_{19}$Cl${}_8$: a distorted kagome antiferromagnet

Abstract

We present the crystal structure and magnetic properties of Y${}_3$Cu${}_9$(OH)${}_{19}$Cl${}_8$, a stoichiometric frustrated quantum spin system with slightly distorted kagome layers. Single crystals of Y${}_3$Cu${}_9$(OH)${}_{19}$Cl${}_8$ were grown under hydrothermal conditions. The structure was determined from single crystal X-ray diffraction and confirmed by neutron powder diffraction. The observed structure reveals two different Cu-positions leading to a slightly distored kagome layer in contrast to the closely related YCu${}_3$(OH)${}_6$Cl${}_3$. Curie-Weiss behavior at high-temperatures with a Weiss-temperature ${\theta }_W$ of the order of $-100$ K, shows a large dominant antiferromagnetic coupling within the kagome planes. Specific-heat and magnetization measurements on single crystals reveal an antiferromagnetic transition at T${}_N=2.2$ K indicating a pronounced frustration parameter of ${\theta }_W/T_N\approx 50$. Optical transmission experiments on powder samples and single crystals confirm the structural findings. Specific-heat measurements on YCu${}_3$(OH)${}_6$Cl${}_3$ down to 0.4 K confirm the proposed quantum spin-liquid state of that system. Therefore, the two Y-Cu-OH-Cl compounds present a unique setting to investigate closely related structures with a spin-liquid state and a strongly frustrated AFM ordered state, by slightly releasing the frustration in a kagome lattice.

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Cited by in corpus (3)

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• Local study of the insulating quantum kagome antiferromagnets YCu3(OH)6OxCl3-x (x=0,1/3)
• Nature of optical excitations in the frustrated kagome compound Herbertsmithite