2017/07/23 by Jonas Sonnenschein, Johannes Reuther
Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Degenerate energy levels #Electron #Ising model #Physics #Quantum #Quantum many-body systems #Quantum mechanics #Quantum spin liquid #Quasiparticle #Spin (aerodynamics) #Spin polarization #Spinon #Square lattice #Superconductivity #Symmetry protected topological order #Topological Materials and Phenomena #Topological degeneracy #Topological order #Topological quantum computer #Topology (electrical circuits) #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.96.235113
published as Phys. Rev. B 96, 235113 (2017) · 16 pages, 7 figures
arxiv created 2017/07/23 · openalex publication_date 2017/12/11 · arxiv updated 2017/12/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Spin liquids are exotic quantum states characterized by the existence of fractional and deconfined quasiparticle excitations, referred to as spinons and visons. Their fractional nature establishes topological properties such as a protected ground-state degeneracy. This work investigates spin-orbit coupled spin liquids where, additionally, topology enters via nontrivial band structures of the spinons. We revisit the ℤ2 spin-liquid phases that have recently been identified in a projective symmetry-group analysis on the square lattice when spin-rotation symmetry is maximally lifted [J. Reuther et al., Phys. Rev. B 90, 174417 (2014)]. We find that in the case of nearest-neighbor couplings only, ℤ2 spin liquids on the square lattice always exhibit trivial spinon bands. Adding second-neighbor terms, the simplest projective symmetry-group solution closely resembles the Bernevig-Hughes-Zhang model for topological insulators. Assuming that the emergent gauge fields are static, we investigate vison excitations, which we confirm to be deconfined in all investigated spin phases. Particularly, if the spinon bands are topological, the spinons and visons form bound states consisting of several spinon-Majorana zero modes coupling to one vison. The existence of such zero modes follows from an exact mapping between these spin phases and topological p+ip superconductors with vortices. We propose experimental probes to detect such states in real materials.