Thermodynamic Properties of Three-Dimensional Orthogonal Dimer Model for SrCu$_2$(BO$_3$)$_2$
Thermodynamic Properties of Three-Dimensional Orthogonal Dimer Model for SrCu$_2$(BO$_3$)$_2$
复制标题
SrCu$_2$(BO$_3$)$_2$三维正交二聚体模型的热力学性质
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
K. Ueda
中科院分区：
文献类型：
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作者：
S. Miyahara;K. Ueda
讨论了正交二聚体SrCu $_2 $（BO $_3 $）$_2$的层间耦合效应。的三维模型的自旋间隙$\Delta$是独立的层间耦合时，他们是小的。因此，在低温下（$T < \Delta$）的热力学性质的二维模型很好地描述。另一方面，在高温下，平均场型标度系数对于讨论弱层间耦合的磁化率是有用的。
根据磁化率拟合，估算出最近邻耦合的耦合常数为J = 85 K，次最近邻耦合的耦合常数为$J^K“}= 54$ K，层间耦合的耦合常数为$J^K”} = 8$ K。这些参数与低温下比热随温度的变化关系是一致的。
Effects of the inter-layer couplings for the orthogonal dimer system SrCu$_2$(BO$_3$)$_2$ are discussed. The spin-gap $\Delta$ of the three-dimensional model is independent of the inter-layer couplings when they are small. Therefore at low temperatures ($T < \Delta$) thermodynamic properties are described well by the two-dimensional model. On the other hand at high temperatures the mean-field type scaling ansatz is useful to discuss the magnetic susceptibility for week inter-layer couplings.
From fit of the magnetic susceptibility, the estimated coupling constants are J = 85 K for the nearest-neighbor couplings, $J^{'} = 54$ K for the next-nearest-neighbor couplings, and $J^{''} = 8$ K for the inter-layer couplings. These parameters are consistent with the temperature dependence of the specific heat at low temperatures.