School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
Nat Commun. 2018 Apr 23;9(1):1575. doi: 10.1038/s41467-018-03934-1.
Quantum spin liquids (QSLs) have been at the forefront of correlated electron research ever since their proposal in 1973, and the realization that they belong to the broader class of intrinsic topological orders. According to received wisdom, QSLs can arise in frustrated magnets with low spin S, where strong quantum fluctuations act to destabilize conventional, magnetically ordered states. Here, we present a Z QSL ground state that appears already in the semiclassical, large-S limit. This state has both topological and symmetry-related ground-state degeneracy, and two types of gaps, a "magnetic flux" gap that scales linearly with S and an "electric charge" gap that drops exponentially in S. The magnet is the spin-S version of the spin-1/2 Kitaev honeycomb model, which has been the subject of intense studies in correlated electron systems with strong spin-orbit coupling, and in optical lattice realizations with ultracold atoms.
量子自旋液体 (QSL) 自 1973 年提出以来一直是关联电子研究的前沿领域，并且它们属于更广泛的内在拓扑序类别。根据公认的观点，QSL 可以在具有低自旋 S 的受挫磁体中出现，其中强量子涨落作用会破坏传统的、磁有序状态。在这里，我们提出了一个在半经典、大 S 极限下出现的 Z QSL 基态。这个状态既有拓扑的又有与对称相关的基态简并性，还有两种间隙，一种是与 S 线性标度的“磁通量”间隙，另一种是在 S 中呈指数下降的“电荷”间隙。该磁体是自旋 S 的版本的自旋 1/2 Kitaev 蜂窝模型，该模型一直是具有强自旋轨道耦合的关联电子系统和具有超冷原子的光学晶格实现中的研究热点。
