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arXiv 0705.0654cond-mat.str-el
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实验性$S=1/2$ kagomé反铁磁体的磁基态

The magnetic groundstate of an experimental $S=1/2$ kagomé antiferromagnet

M. A. de Vries, K. V. Kamenev, W. A. Kockelmann, J. Sanchez-Benitez, A. Harrison

摘要:

用$x=1$对锌副氯铜矿Zn $_x$ Cu $_{4-x}$(OH)$_6$ Cl $_2$进行了中子粉末衍射测量,研究了$0.5 \leq x \leq 1$在9 T以下的热容量。$x=1$相最近被证明是$S=1/2$ kagomé反铁磁体的杰出实现。使用中子衍射观察到Cu和Zn位点之间的Cu $^{2+}$ /Zn $^{2+}$的弱混合,对应于$x=1$的所有Cu $^{2+}$的$\sim 9$ %。这种"反位无序“为$0.8 \leq x \leq 1$的热容量的场依赖性提供了一致的解释。从推导出的Cu $^{2+}$占据的锌位的$x = 0.8... 1$与磁化率的比较,我们认为,对于$x = 0.8... 1$锌副氯镁石是一种自旋液体没有自旋间隙。不成对的,但强烈相互作用的自旋的存在下,产生了宏观退化的基态流形,随着$x$降低,玻璃态动力学越来越强。

英文摘要:

We have carried out neutron powder-diffraction measurements on zinc paratacamite Zn$_x$Cu$_{4-x}$(OH)$_6$Cl$_2$ with $x=1$, and studied the heat capacity in fields of up to 9 T for $0.5 \leq x \leq 1$. The $x=1$ phase has recently been shown to be an outstanding realisation of the $S=1/2$ kagomé antiferromagnet. A weak mixing of Cu$^{2+}$/Zn$^{2+}$ between the Cu and the Zn sites, corresponding to $\sim 9$% of all Cu$^{2+}$ for $x=1$, is observed using neutron diffraction. This ``antisite disorder'' provides a consistent explanation of the field dependence of the heat capacity for $0.8 \leq x \leq 1$. From comparison of the derived Cu$^{2+}$ occupancy of the Zn sites for $x = 0.8... 1$ with the magnetic susceptibility, we argue that for $x = 0.8... 1$ zinc paratacamite is a spin liquid without a spin gap. The presence of unpaired but nevertheless strongly interacting spins gives rise to a macroscopically degenerate ground state manifold, with increasingly glassy dynamics as $x$ is lowered.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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