标题： 自旋激发的Shastry-Sutherland模型——亚铁磁性和近似非约束量子临界性 显示英文标题

标题： Spin excitations of the Shastry-Sutherland model -- altermagnetism and proximate deconfined quantum criticality

摘要： 对称性在凝聚态物理中起着关键作用。 在量子磁学中，它决定了许多奇特的现象，包括非禁闭量子临界性和反铁磁性。 在此，通过研究$S=1/2$反铁磁 Shastry-Sutherland 模型的自旋激发，我们表明该模型中的 Néel 反铁磁态是一种反铁磁体，其特征是两个手性磁子带之间存在非相对论性的分裂。 此外，我们在纵向激发通道中识别出一个希格斯模，其能隙在接近反铁磁到晶格价键固体转变时变软，暗示了几乎非禁闭激发的出现。 然而，在转变过程中，两个磁子带（戈德斯通模）之间的分裂仍然保持有限。 这些结果表明，该转变是弱一阶的，并且接近一个假设的非禁闭量子临界点。 我们发现，反铁磁性提供了一种敏感的方法来探测非禁闭量子临界性。 显示英文摘要

摘要： Symmetry plays a crucial role in condensed matter physics. In quantum magnetism, it dictates a number of exotic phenomena, including deconfined quantum criticality and altermagnetism. Here, by studying the spin excitations of the $S=1/2$ antiferromagnetic Shastry-Sutherland model, we show that the N\'eel antiferromagnetic state in this model is an altermagnet featuring a non-relativistic splitting between two chiral magnon bands. Moreover, we identify a Higgs mode in the longitudinal excitation channel, whose gap softens when approaching the antiferromagnetic to plaquette valence bond solid transition, implying the appearance of nearly deconfined excitations. However, the splitting between the two magnon bands (Goldstone modes) remains finite at the transition. These results indicate that the transition is weakly first-order and proximate to a putative deconfined quantum critical point. We find that the altermagnetism provides a sensitive means to probe the deconfined quantum criticality.