The magnetic groundstate of an experimental $S=1/2$ kagomé antiferromagnet

Abstract

We have carried out neutron powder-diffraction measurements on zinc paratacamite Zn${}_x$Cu${}_{4-x}$(OH)${}_6$Cl${}_2$ with $x=1$, and studied the heat capacity in fields of up to 9 T for $0.5\le x\le 1$. The $x=1$ phase has recently been shown to be an outstanding realisation of the $S=1/2$ kagomé antiferromagnet. A weak mixing of Cu${}^{2+}$/Zn${}^{2+}$ between the Cu and the Zn sites, corresponding to $\sim 9$% of all Cu${}^{2+}$ for $x=1$, is observed using neutron diffraction. This ``antisite disorder'' provides a consistent explanation of the field dependence of the heat capacity for $0.8\le x\le 1$. From comparison of the derived Cu${}^{2+}$ occupancy of the Zn sites for $x=\mathrm{0.8...1}$ with the magnetic susceptibility, we argue that for $x=\mathrm{0.8...1}$ zinc paratacamite is a spin liquid without a spin gap. The presence of unpaired but nevertheless strongly interacting spins gives rise to a macroscopically degenerate ground state manifold, with increasingly glassy dynamics as $x$ is lowered.

Thorough revision of manuscript. Added 1 figure. Manuscript submitted to Physics Review Letters

References in corpus (7)

• Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2
• Projected wavefunction study of Spin-1/2 Heisenberg model on the Kagome lattice
• Quantum magnetism in the paratacamite family: towards an ideal kagome lattice
• 17O NMR study of the intrinsic magnetic susceptibility and spin dynamics of the quantum kagome antiferromagnet ZnCu3(OH)6Cl2
• ^{63}Cu, ^{35}Cl, and ^{1}H NMR in the S=1/2 Kagomé Lattice ZnCu_{3}(OH)_{6}Cl_{2}
• Low temperature magnetization of the S=1/2 kagome antiferromagnet ZnCu_3(OH)_6Cl_2
• Quantum dimer model with Z_2 liquid ground-state: interpolation between cylinder and disk topologies and toy model for a topological quantum-bit

Cited by in corpus (56)

• Properties of an algebraic spin liquid on the kagome lattice
• Dzyaloshinsky-Moriya Anisotropy in the Spin-1/2 Kagomé Compound ZnCu${}_3$(OH)${}_6$Cl${}_2$
• Doped Kagome System as Exotic Superconductor
• The Chemistry of Quantum Spin Liquids
• Projected wave function study of Z2 spin liquids on the kagome lattice for the spin-1/2 quantum Heisenberg antiferromagnet
• Dynamic Scaling in the Susceptibility of the Spin-1\2 Kagome Lattice Antiferromagnet Herbertsmithite
• Extension of the spin-1/2 frustrated square lattice model: the case of layered vanadium phosphates
• Spin liquid behaviour in Jeff=1/2 triangular lattice Ba3IrTi2O9
• Modified kagome physics in the natural spin-1/2 kagome lattice systems - kapellasite Cu3Zn(OH)6Cl2 and haydeeite Cu3Mg(OH)6Cl2
• Valence-bond crystal in the extended kagome spin-1/2 quantum Heisenberg antiferromagnet: A variational Monte Carlo approach
• Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_x$(OH)${}_{1-x}$]
• Spin dynamics and disorder effects in the S=1/2 kagome Heisenberg spin liquid phase of kapellasite
• From Spin Glass to Quantum Spin Liquid Ground States in Molybdate Pyrochlores
• Dzyaloshinskii-Moriya anisotropy and non-magnetic impurities in the $s=1/2$ kagome system ZnCu_3(OH)_6Cl_2
• Spontaneous formation of a non-uniform chiral spin liquid in moat-band lattices
• Symmetry Reduction in the Quantum Kagome Antiferromagnet Herbertsmithite
• Local Spin Susceptibility of the S=1/2 Kagome Lattice in ZnCu3(OD)6Cl2
• Gapless Spin Liquid Behavior in A Kagome Heisenberg Antiferromagnet with Randomly Distributed Hexagons of Alternate Bonds
• Valence-bond crystals in the kagome spin-1/2 Heisenberg antiferromagnet: a symmetry classification and projected wave function study
• Heat Transport in Herbertsmithite: Can a Quantum Spin Liquid Survive Disorder?
• Gapless quantum spin liquid in the triangular system Sr${}_3$CuSb${}_2$O${}_9$
• A Cu2+ (S = 1/2) Kagomé Antiferromagnet: MgxCu4-x(OH)6Cl2
• Monopole Quantum Numbers in the Staggered Flux Spin Liquid
• Gutzwiller-projected states for the $J_1$-$J_2$ Heisenberg model on the kagome lattice: achievements and pitfalls
• External magnetic field effects on a distorted kagome antiferromagnet
• Spin-1/2 Heisenberg antiferromagnet on an anisotropic kagome lattice
• Weak Ferromagnetic Exchange and Anomalous Specific Heat in ZnCu3(OH)6Cl2
• Spin-1/2 kagome compounds: volborthite vs herbertsmithite
• The observation of quantum fluctuations in a kagome Heisenberg antiferromagnet
• Unconventional Magnetic Oscillations in Kagome Mott Insulators
• Spin Triplet Excitations for a Valence Bond Solid on the Kagome Lattice
• The symmetry of the spin Hamiltonian in herbertsmithite, a spin-1/2 kagomé lattice
• Nature of optical excitations in the frustrated kagome compound Herbertsmithite
• Scaling in Dynamic Susceptibility of Herbertsmithite and Heavy-Fermion Metals
• Specific Heat of the Kagome Antiferromagnet Herbertsmithite in High Magnetic Fields
• Nonlocal effects of low-energy excitations in quantum-spin-liquid candidate Cu${}_3$Zn(OH)${}_6$FBr
• Structure factor of low-energy spin excitations in a S=1/2 kagome antiferromagnet
• Quantum phases of the frustrated XY models on the honeycomb lattice
• Structures of magnetic excitations in the spin-1/2 kagome-lattice antiferromagnets Cs${}_2$Cu${}_3$SnF${}_{12}$ and Rb${}_2$Cu${}_3$SnF${}_{12}$
• Perfect kagome-lattice antiferromagnets with J${}_{eff}$ = 1/2: The Co${}^{2+}$-analogs of copper minerals volborthite and vesignieite
• Magnetic ground states in kagome YCu${}_3$(OH)${}_6$[(Cl${}_x$Br${}_{1-x}$)${}_{3-y}$(OH)${}_y$]
• Infrared phonons as a probe of a spin-liquid states in herbertsmithite ZnCu3(OH)6Cl2
• Magnetic ordering of the distorted kagome antiferromagnet Y${}_3$Cu${}_9$(OH)${}_{18}$[Cl${}_8$(OH)] prepared via optimal synthesis
• Heat conduction in herbertsmithite: field dependence at the onset of the quantum spin liquid regime
• Role of chemical pressure on the electronic and magnetic properties of spin-1/2 kagome mineral averievite
• Thermodynamic evidence of fermionic behavior in the vicinity of one-ninth plateau in a kagome antiferromagnet
• Piercing the Dirac spin liquid: From a single monopole to chiral states
• Strongly correlated Fermi systems as a new state of matter
• Combinatorial exploration of quantum spin liquid candidates in the herbertsmithite material family
• Chemo-Structural Disorder in the kagomé spin $S$ = 1/2 systems ZnCu${}_3$(OH)${}_6$Cl${}_2$ and YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_x$(OH)${}_{1-x}$]
• Magnetic effects of non-magnetic impurities in gapped short-range resonating valence bond spin liquids
• Magnetic excitations in the 1/3 plateau state in InCu${}_3$(OH)${}_6$Cl${}_3$
• Spin excitations arising from anisotropic Dirac spinons in YCu${}_3$(OD)${}_6$Br${}_2$[Br${}_{0.33}$(OD)${}_{0.67}$]
• Recent progress in quantum spin liquids, fractional magnetization plateaus, and unconventional superconductivity in kagome lattices
• Spinon mediation of witness spin dynamics in herbertsmithite
• Spin Liquid Mimicry in the Hydroxide Double Perovskite CuSn(OH)${}_6$ Induced by Correlated Proton Disorder