Spinon heat transport and spin-phonon interaction in the spin-1/2 Heisenberg chain cuprates Sr2CuO3 and SrCuO2
Spinon heat transport and spin-phonon interaction in the spin-1/2 Heisenberg chain cuprates Sr2CuO3 and SrCuO2
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DOI：
10.1088/1742-5468/2012/03/p03006
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发表时间：
2012-03-01
影响因子：
2.4
通讯作者：
Hess, C.
中科院分区：
文献类型：
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作者：
Hlubek, N.;Zotos, X.;Hess, C.
我们研究了自旋链化合物Sr_2CuO_3的高纯单晶的热导率k（mag），这被认为是一维自旋1/2反铁磁海森堡模型的一个很好的实现。我们发现，自旋热导率k（mag）是强烈增强，与以前的结果相比，样品具有较低的化学纯度。k（mag）的分析允许计算自旋平均自由程l（mag）作为温度的函数。在低温下，我们发现l（mag）类似于0.5 μ m，对应于1200多个链晶胞。随着温度的升高，平均自由程强烈减小，并接近类似于（1/T）exp（T-u*/T）的指数衰减，这是具有能量标度k（B）T（u）* 的Umklapp过程的特征。基于Matthiessen规则，我们将lmag分解为与温度无关的自旋-缺陷散射长度l（0）和与温度相关的自旋-声子散射长度l（sp）（T）。通过比较Sr_2CuO_3和SrCuO_2的l（mag）（T），我们发现两个体系中的自旋-声子相互作用（用l（sp）表示）实际上是相同的。经验推导的l（sp）与模型计算的自旋-声子相互作用的一维自旋-1/2 XY模型的比较产生合理的协议与实验数据。
We have investigated the thermal conductivity k(mag) of high-purity single crystals of the spin chain compound Sr2CuO3, which is considered an excellent realization of the one-dimensional spin-1/2 antiferromagnetic Heisenberg model. We find that the spinon heat conductivity k(mag) is strongly enhanced as compared to previous results obtained on samples with lower chemical purity. The analysis of k(mag) allows the computation of the spinon mean free path l(mag) as a function of temperature. At low temperature we find l(mag) similar to 0.5 mu m, corresponding to more than 1200 chain unit cells. Upon increasing the temperature, the mean free path decreases strongly and approaches an exponential decay similar to(1/T) exp (T-u*/T), which is characteristic for Umklapp processes with the energy scale k(B)T(u)*. Based on Matthiessen's rule we decompose lmag into a temperature-independent spinon-defect scattering length l(0) and a temperature-dependent spinon-phonon scattering length l(sp)(T). By comparing l(mag)(T) of Sr2CuO3 with that of SrCuO2, we show that the spin-phonon interaction, as expressed by l(sp), is practically the same in both systems. The comparison of the empirically derived l(sp) with model calculations for the spin-phonon interaction of the one-dimensional spin-1/2 XY model yields reasonable agreement with the experimental data.