Lozano-Gómez Daniel, Noculak Vincent, Oitmaa Jaan, Singh Rajiv R P, Iqbal Yasir, Reuther Johannes, Gingras Michel J P
Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Institut für Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Dresden 01062, Germany.
Proc Natl Acad Sci U S A. 2024 Sep 3;121(36):e2403487121. doi: 10.1073/pnas.2403487121. Epub 2024 Aug 28.
Gauge theories are powerful theoretical physics tools that allow complex phenomena to be reduced to simple principles and are used in both high-energy and condensed matter physics. In the latter context, gauge theories are becoming increasingly popular for capturing the intricate spin correlations in spin liquids, exotic states of matter in which the dynamics of quantum spins never ceases, even at absolute zero temperature. We consider a spin system on a three-dimensional pyrochlore lattice where emergent gauge fields not only describe the spin liquid behavior at zero temperature but crucially determine the system's temperature evolution, with distinct gauge fields giving rise to different spin liquid phases in separate temperature regimes. Focusing first on classical spins, in an intermediate temperature regime, the system shows an unusual coexistence of emergent vector and tensor gauge fields where the former is known from classical spin ice systems while the latter has been associated with fractonic quasiparticles, a peculiar type of excitation with restricted mobility. Upon cooling, the system transitions into a low-temperature phase where an entropic selection mechanism depopulates the degrees of freedom associated with the tensor gauge field, rendering the system spin-ice-like. We further provide numerical evidence that in the corresponding quantum model, a spin liquid with coexisting vector and tensor gauge fields has a finite window of stability in the parameter space of spin interactions down to zero temperature. Finally, we discuss the relevance of our findings for non-Kramers magnetic pyrochlore materials.
规范理论是强大的理论物理工具，它能将复杂现象简化为简单原理，在高能物理和凝聚态物理中均有应用。在后一种情况下，规范理论在捕捉自旋液体中复杂的自旋关联方面正变得越来越流行，自旋液体是一种奇异的物质状态，即使在绝对零度时，量子自旋的动力学也不会停止。我们考虑一个三维焦绿石晶格上的自旋系统，其中涌现的规范场不仅描述了零温度下的自旋液体行为，而且关键地决定了系统的温度演化，不同的规范场在不同的温度区间产生不同的自旋液相。首先关注经典自旋，在中间温度区间，系统呈现出涌现的矢量和张量规范场的异常共存，其中前者在经典自旋冰系统中是已知的，而后者与分数子准粒子相关联，分数子准粒子是一种具有受限迁移率的特殊激发类型。冷却时，系统转变为低温相，在该相中，一种熵选择机制减少了与张量规范场相关的自由度，使系统类似自旋冰。我们进一步提供了数值证据，表明在相应的量子模型中，具有共存矢量和张量规范场的自旋液体在自旋相互作用的参数空间中直至零温度都有一个有限的稳定窗口。最后，我们讨论了我们的发现与非克莱默斯磁性焦绿石材料的相关性。
