Theoretische Physik, ETH Zürich, CH-8093 Zürich, Switzerland.
Institut de Théorie des Phénomènes Physiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2014 Apr 11;112(14):147203. doi: 10.1103/PhysRevLett.112.147203. Epub 2014 Apr 10.
Using infinite projected entangled-pair states, we show that the Shastry-Sutherland model in an external magnetic field has low-magnetization plateaus which, in contrast to previous predictions, correspond to crystals of bound states of triplets, and not to crystals of triplets. The first sizable plateaus appear at magnetization 1/8, 2/15 and 1/6, in agreement with experiments on the orthogonal-dimer antiferromagnet SrCu2(BO3)2, and they can be naturally understood as regular patterns of bound states, including the intriguing 2/15 one. We also show that, even in a confined geometry, two triplets bind into a localized bound state with Sz=2. Finally, we discuss the role of competing domain-wall and supersolid phases, as well as that of additional anisotropic interactions.
利用无穷投影纠缠对态，我们表明在外磁场中的 Shastry-Sutherland 模型具有低磁化平台，与之前的预测相反，这些平台对应于三重态束缚态的晶体，而不是三重态的晶体。第一个相当大的平台出现在磁化强度为 1/8、2/15 和 1/6，与正交二聚体反铁磁体 SrCu2(BO3)2 的实验结果一致，它们可以自然地理解为束缚态的规则图案，包括有趣的 2/15 图案。我们还表明，即使在受限的几何形状中，两个三重态也会结合成一个具有 Sz=2 的局域束缚态。最后，我们讨论了竞争的畴壁和超流相以及附加各向异性相互作用的作用。
