Changlani Hitesh J, Kochkov Dmitrii, Kumar Krishna, Clark Bryan K, Fradkin Eduardo
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Phys Rev Lett. 2018 Mar 16;120(11):117202. doi: 10.1103/PhysRevLett.120.117202.
Frustrated quantum magnets are a central theme in condensed matter physics due to the richness of their phase diagrams. They support a panoply of phases including various ordered states and topological phases. Yet, this problem has defied a solution for a long time due to the lack of controlled approximations which make it difficult to distinguish between competing phases. Here we report the discovery of a special quantum macroscopically degenerate point in the XXZ model on the spin-1/2 kagome quantum antiferromagnet for the ratio of Ising to antiferromagnetic transverse coupling J_{z}/J=-1/2. This point is proximate to many competing phases explaining the source of the complexity of the phase diagram. We identify five phases near this point including both spin-liquid and broken-symmetry phases and give evidence that the kagome Heisenberg antiferromagnet is close to a transition between two phases.
受挫量子磁体因其丰富的相图而成为凝聚态物理的核心主题。它们支持一系列相，包括各种有序态和拓扑相。然而，由于缺乏可控的近似方法，使得难以区分相互竞争的相，这个问题长期以来一直没有得到解决。在此，我们报告在自旋-1/2 Kagome 量子反铁磁体的 XXZ 模型中，对于伊辛与反铁磁横向耦合比 J_z/J = -1/2 时，发现了一个特殊的量子宏观简并点。这个点靠近许多相互竞争的相，解释了相图复杂性的根源。我们确定了该点附近的五个相，包括自旋液体相和破缺对称相，并给出证据表明 Kagome 海森堡反铁磁体接近两个相之间的转变。
