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Magnetism of Cu_6 Ge_6 O_{18}-x H_2 O (x = 0 ~ 6), a compound of the one-dimensional Heisenberg $S = 1/2$ model with competing antiferromagnetic interactions

Masashi Hase·Kiyoshi Ozawa·Norio Shinya
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Abstract

We measured the magnetic susceptibilities of Cu$_6$Ge$_6$O$_{18}$-xH$_2$O ($x = 0 \sim 6$). Susceptibility above the antiferromagnetic (AF) transition temperature ($T_{\rm N}$) agrees with susceptibility of the one-dimensional Heisenberg $S = 1/2$ model with competing AF interactions. From the estimated ratio between nearest-neighbor and next-nearest-neighbor AF exchange interactions, the spin system is probably located near a boundary between spin systems with gapless and gapped magnetic excitation. The value of $T_{\rm N}/T_{\rm max}$, where $T_{\rm max}$ is temperature at which the susceptibility is maximum, shows a unique dependence on $x$. The $x$ dependence can be explained qualitatively by taking phase transition as a function of $x$ and the effect of disorder into account.

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Masashi Hase, Kiyoshi Ozawa, Norio Shinya. 2003-04-15. Magnetism of Cu_6 Ge_6 O_{18}-x H_2 O (x = 0 ~ 6), a compound of the one-dimensional Heisenberg $S = 1/2$ model with competing antiferromagnetic interactions. https://arxiv.org/abs/cond-mat/0304323

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