Yoshitake Junki, Nasu Joji, Motome Yukitoshi
Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan.
Phys Rev Lett. 2016 Oct 7;117(15):157203. doi: 10.1103/PhysRevLett.117.157203.
Experimental identification of quantum spin liquids remains a challenge, as the pristine nature is to be seen in asymptotically low temperatures. We here theoretically show that the precursor of quantum spin liquids appears in the spin dynamics in the paramagnetic state over a wide temperature range. Using the cluster dynamical mean-field theory and the continuous-time quantum Monte Carlo method, which are newly developed in the Majorana fermion representation, we calculate the dynamical spin structure factor, relaxation rate in nuclear magnetic resonance, and magnetic susceptibility for the honeycomb Kitaev model whose ground state is a canonical example of the quantum spin liquid. We find that dynamical spin correlations show peculiar temperature and frequency dependence even below the temperature where static correlations saturate. The results provide the experimentally accessible symptoms of the fluctuating fractionalized spins evincing the quantum spin liquids.
量子自旋液体的实验识别仍然是一个挑战，因为其原始特性只能在渐近低温下才能显现。我们在此从理论上表明，量子自旋液体的前驱体出现在顺磁态自旋动力学的较宽温度范围内。利用在马约拉纳费米子表示中新发展的团簇动力学平均场理论和连续时间量子蒙特卡罗方法，我们计算了蜂窝状基泰耶模型的动态自旋结构因子、核磁共振弛豫率和磁化率，该模型的基态是量子自旋液体的典型例子。我们发现，即使在静态关联达到饱和的温度以下，动态自旋关联也表现出特殊的温度和频率依赖性。这些结果提供了波动的分数化自旋的实验可及特征，表明了量子自旋液体的存在。
