Evidence for the topological order in a kagome antiferromagnet

Abstract

A Z2 quantum spin liquid hosts one of the simplest topological orders and exhibits many exotic properties due to long-range quantum entanglements. Its elementary excitations are anyons such as spinons carrying fractionalized spin quantum number and visons carrying emergent Z2 gauge flux. However, experimental detection of these anyons remains elusive. The difficulties lie not only in the fact that there exists few candidates for Z2 quantum spin liquids but also in that visons are magnetically inert hence immune to available experimental techniques. Here we have studied the spin excitations and specific heats of kagome-lattice antiferromagnet Cu${}_4$(OH)${}_6$FBr and Cu${}_3$Zn(OH)${}_6$FBr, which consists of two-dimensional Cu${}^{2+}$ kagome layers with either Cu${}^{2+}$ or Zn${}^{2+}$ ions in between. By combining the first principle calculations and inelastic neutron scattering data in the former, we show that the dominate couplings in Cu${}_4$(OH)${}_6$FBr are between the nearest neighbor spins within the kagome planes, and the kagome and interlayer spin systems are essentially decoupled above the antiferromagnetic transition temperature. The intrinsic spin excitations and specific heats of the kagome layers for Cu${}_3$Zn(OH)${}_6$FBr are thus derived by removing the contributions from the residual interlayer Cu${}^{2+}$ magnetic impurities. Accordingly, the kagome spin system exhibits spin continuum with momentum-dependent spin gap and a large magnetic entropy at low temperature that is insensitive to magnetic field, which can be understood as the evidences of spinons and visons in this kagome quantum spin liquid candidate. Our results suggest the existence of the Z2 anyons in the material, and therefore provide a comprehensive set of evidences for the Z2 topological order in kagome quantum spin liquid and bring their choreographed entanglement dances to the stage of real materials.

arXiv comment11 pages, 8 figures

References in corpus (31)

• Topological Insulators
• Topological insulators and superconductors
• Fault-tolerant quantum computation by anyons
• Non-Abelian Anyons and Topological Quantum Computation
• Quantum Spin Liquid States
• Spin Liquid Ground State of the $S=1/2$ Kagome Heisenberg Model
• Fault-tolerant quantum computation with high threshold in two dimensions
• Z_2 Gauge Theory of Electron Fractionalization in Strongly Correlated Systems
• Identifying Topological Order by Entanglement Entropy
• Herbertsmithite and the Search for the Quantum Spin Liquid
• Predicting the Spin-Lattice Order of Frustrated Systems from First-Principles
• Quasi-adiabatic Continuation of Quantum States: The Stability of Topological Ground State Degeneracy and Emergent Gauge Invariance
• Gapless spin-liquid ground state in the $S=1/2$ kagome antiferromagnet
• Translational symmetry and microscopic constraints on symmetry-enriched topological phases: a view from the surface
• The magnetic groundstate of an experimental $S=1/2$ kagomé antiferromagnet
• Spin-glass ground state in a triangular-lattice compound YbZnGaO${}_4$
• Physics of low energy singlet states of the Kagome lattice quantum Heisenberg antiferromagnet
• Correlated impurities and intrinsic spin liquid physics in the kagome material Herbertsmithite
• Gapped spin-1/2 spinon excitations in a new kagome quantum spin liquid compound Cu${}_3$Zn(OH)${}_6$FBr
• Gapped spin liquid with ${\mathbb{Z}}_2$-topological order for kagome Heisenberg model
• Scaling and data collapse from local moments in frustrated disordered quantum spin systems
• Topological excitations and the dynamic structure factor of spin liquids on the kagome lattice
• Magnetism of the N=42 kagome lattice antiferromagnet
• Barlowite: A Spin-1/2 Antiferromagnet with a Geometrically Perfect Kagome Motif
• Vison states and confinement transitions of Z2 spin liquids on the kagome lattice
• Dynamical Signature of Symmetry Fractionalization in Frustrated Magnets
• From Claringbullite to a new spin liquid candidate Cu${}_3$Zn(OH)${}_6$FCl
• Quantum Spin Liquid with Even Ising Gauge Field Structure on Kagome Lattice
• Effect of Zn doping on the antiferromagnetism in kagome Cu${}_{4-x}$Zn${}_x$(OH)${}_6$FBr
• Diagnosing Fractionalization from the Spin Dynamics of $Z_2$ Spin Liquids on the Kagome Lattice by Quantum Monte Carlo Simulations
• Exact solution of close-packed dimers on the kagome lattice

Cited by in corpus (8)

• Dynamical Signature of Fractionalization at the Deconfined Quantum Critical Point
• Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_x$(OH)${}_{1-x}$]
• Dynamics of Topological Excitations in a Model Quantum Spin Ice
• Dynamical Signature of Symmetry Fractionalization in Frustrated Magnets
• Quantum Spin Liquid with Even Ising Gauge Field Structure on Kagome Lattice
• Effect of Zn doping on the antiferromagnetism in kagome Cu${}_{4-x}$Zn${}_x$(OH)${}_6$FBr
• Diagnosing Fractionalization from the Spin Dynamics of $Z_2$ Spin Liquids on the Kagome Lattice by Quantum Monte Carlo Simulations
• Antiferromagnetism in kagome $\alpha$-Cu${}_3$Mg(OH)${}_6$Br${}_2$