Unifying description of competing orders in two-dimensional quantum magnets

• Published in: Nature communications Vol. 10; no. 1; pp. 4254 - 12
• Main Authors: Song, Xue-Yang, Wang, Chong, Vishwanath, Ashvin, He, Yin-Chen
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.09.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/2792; 639/766/119/997; 639/766/530/2795; Excitation; Fermions; Humanities and Social Sciences; Lattices (mathematics); Magnetic monopoles; Magnets; multidisciplinary; Photons; Physics; Quantum electrodynamics; Science; Science (multidisciplinary); Spin liquid; Symmetry; Two dimensional materials
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-11727-3

Quantum magnets provide the simplest example of strongly interacting quantum matter, yet they continue to resist a comprehensive understanding above one spatial dimension. We explore a promising framework in two dimensions, the Dirac spin liquid (DSL) — quantum electrodynamics (QED 3 ) with 4 Dirac fermions coupled to photons. Importantly, its excitations include magnetic monopoles that drive confinement. We address previously open key questions — the symmetry actions on monopoles on square, honeycomb, triangular and kagome lattices. The stability of the DSL is enhanced on triangular and kagome lattices compared to bipartite (square and honeycomb) lattices. We obtain the universal signatures of the DSL on triangular and kagome lattices, including those of monopole excitations, as a guide to numerics and experiments on existing materials. Even when unstable, the DSL helps unify and organize the plethora of ordered phases in correlated two-dimensional materials. The Dirac spin liquid is a candidate description for the strongly correlated behaviour of some quantum magnets. Song et al. study the symmetry dependence physics of monopole excitations and argue that the lattice-dependent consequences for magnetic ordering may provide a unifying picture for 2D quantum magnetism.