Ran Kejing, Wang Jinghui, Wang Wei, Dong Zhao-Yang, Ren Xiao, Bao Song, Li Shichao, Ma Zhen, Gan Yuan, Zhang Youtian, Park J T, Deng Guochu, Danilkin S, Yu Shun-Li, Li Jian-Xin, Wen Jinsheng
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
Phys Rev Lett. 2017 Mar 10;118(10):107203. doi: 10.1103/PhysRevLett.118.107203. Epub 2017 Mar 7.
Kitaev interactions underlying a quantum spin liquid have long been sought, but experimental data from which their strengths can be determined directly, are still lacking. Here, by carrying out inelastic neutron scattering measurements on high-quality single crystals of α-RuCl_{3}, we observe spin-wave spectra with a gap of ∼2 meV around the M point of the two-dimensional Brillouin zone. We derive an effective-spin model in the strong-coupling limit based on energy bands obtained from first-principles calculations, and find that the anisotropic Kitaev interaction K term and the isotropic antiferromagnetic off-diagonal exchange interaction Γ term are significantly larger than the Heisenberg exchange coupling J term. Our experimental data can be well fit using an effective-spin model with K=-6.8 meV and Γ=9.5 meV. These results demonstrate explicitly that Kitaev physics is realized in real materials.
长期以来，人们一直在寻找量子自旋液体背后的基泰耶相互作用，但仍缺乏能够直接确定其强度的实验数据。在此，通过对高质量α-RuCl₃单晶进行非弹性中子散射测量，我们在二维布里渊区的M点附近观察到了一个约2 meV能隙的自旋波谱。我们基于第一性原理计算得到的能带，在强耦合极限下推导了一个有效自旋模型，发现各向异性的基泰耶相互作用K项和各向同性的反铁磁非对角交换相互作用Γ项显著大于海森堡交换耦合J项。使用K = -6.8 meV和Γ = 9.5 meV的有效自旋模型，我们的实验数据能够得到很好的拟合。这些结果明确表明，基泰耶物理在真实材料中得以实现。
