Rapid filling of the spin gap with temperature in the Schwinger-boson mean-field theory of the antiferromagnetic Heisenberg kagome model
Rapid filling of the spin gap with temperature in the Schwinger-boson mean-field theory of the antiferromagnetic Heisenberg kagome model
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DOI：
10.1103/physrevb.99.155151
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发表时间：
2018-07
影响因子：
3.7
通讯作者：
Jad C. Halimeh;Rajiv R. P. Singh
中科院分区：
文献类型：
--
作者：
Jad C. Halimeh;Rajiv R. P. Singh
利用Schwinger玻色子平均场理论，计算了自旋为1/2的反铁磁Heisenberg kagome模型在低温下的动态自旋结构因子。我们发现，自旋间隙迅速填充温度，与强大的低能量谱权重开发的温度为0.05J $，远低于自旋间隙本身和任何明显的自旋密度上升或零温度平均场参数的变化之前。在更高的温度下，自旋子密度迅速增加，导致Schwinger玻色子方法的崩溃。我们的结果可能有助于在$\mathbb{Z}_2$量子自旋液体框架下解释在kagome Herbertsmithite中子散射实验中观察到的低能谱权重。
Using Schwinger boson mean-field theory, we calculate the dynamic spin structure factor at low temperatures $0<T\ll J$ for the spin-$1/2$ antiferromagnetic Heisenberg kagome model, which at $T=0$ hosts a gapped $\mathbb{Z}_2$ spin liquid phase. We find that the spin gap rapidly fills with temperature, with robust low-energy spectral weight developing by a temperature of $0.05J$, well below the spin gap itself and before any appreciable rise in spinon density or change in zero-temperature mean-field parameters. At still higher temperatures, the spinon density increases rapidly leading to a breakdown of the Schwinger boson approach. Our results may help to explain the low-energy spectral weight observed in the neutron scattering experiments on kagome Herbertsmithites within a $\mathbb{Z}_2$ quantum spin-liquid framework.