Magnetic Phase Diagram of Cu_4–xZn_x(OH)₆FBr Studied by Neutron-Diffraction and μSR Techniques*

Wei Yuan, Xiaoyan Ma, Zili Feng, D. T. Adroja, A. D. Hillier, Pabitra Kumar Biswas⃰, Anatoliy Senyshyn, A. Hoser, Jia‐Wei Mei, Zi Yang Meng

Abstract

We have systematically studied the magnetic properties of Cu$_{4-x}$Zn$_x$(OH)$_6$FBr by the neutron diffraction and muon spin rotation and relaxation ($\mu$SR) techniques. Neutron-diffraction measurements suggest that the long-range magnetic order and the orthorhombic nuclear structure in the $x$ = 0 sample can persist up to $x$ = 0.23 and 0.43, respectively. The temperature dependence of the zero-field (ZF) $\mu$SR spectra provide two characteristic temperatures, $T_{A0}$ and $T_{\lambda}$. Comparison between $T_{A0}$ and $T_M$ from previously reported magnetic-susceptibility measurements suggest that the former comes from the short-range interlayer-spin clusters that persist up to $x$ = 0.82. On the other hand, the doping level where $T_{\lambda}$ becomes zero is about 0.66, which is much higher than threshold of the long-range order, i.e., $\sim$ 0.4. Our results suggest that the change in the nuclear structure may alter the spin dynamics of the kagome layers and a gapped quantum-spin-liquid state may exist above $x$ = 0.66 with the perfect kagome planes.

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• Chinese Physics Letters - View
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