新型阻挫量子磁性系统自旋动力学的研究

2006年，A. Kitaev提出了一个简单但是具有强烈交换阻挫的蜂窝晶格自旋模型，其基态是严格可解的自旋液体，而且元激发为Majorana费米子，这使得Kitaev模型吸引了大量的研究兴趣。近年来，人们期望在具有强自旋轨道耦合的新型阻挫量子磁性系统中实现Kitaev自旋液体，但是真实材料中不仅存在Kitaev相互作用，还存在Γ相互作用等其它类型交换作用，而且实验研究的快速发展也为理论研究提出了许多亟待解决的物理问题。在此背景下，本项目以包含海森堡相互作用、Kitaev相互作用和Γ相互作用的J-K-Γ模型为研究对象，开展以自旋动力学为主的理论研究，将阐明新材料中一些奇异物性的物理起源，探寻无序效应可能诱导的新物态，并探索在蜂窝晶格实现量子自旋液体的新途径。而且，我们将进一步推广J-K-Γ模型的研究到三角晶格上，为在新发现的三角晶格自旋液体候选材料中的实验结果提供理论解释。

In 2006, A. Kitaev proposed a simple spin model but with strong exchange frustrations on the honeycomb lattice. Its exactly solvable ground state is a spin liquid and the elementary excitation is the Majorana fermion, which makes the Kitaev model attract a lot of research interest. In recent years, researchers expect to realize the Kitaev spin liquid in the quantum magnetic systems with strong spin-orbit couplings. However, there are not only the Kitaev interaction, but also the Γ interaction and other exchange interactions in the real materials. Moreover, the rapid development of experimental researches also puts forward many physical problems to be solved urgently for theoretical researchers. Under this background, we will take the J-K-Γ model including Heisenberg interaction, Kitaev interaction and Γ interaction as the research object in this project, and focus on its spin dynamics. We will clarify the physical origin of some exotic physical properties in the new materials, explore the new states induced by the disorder effects, and find new ways to realize quantum spin liquid on the honeycomb lattice. Moreover, we will extend the studies of J-K-Γ model to the triangular lattice to provide theoretical explanation for the experimental results in the new candidate spin-liquid materials on the triangular lattice.