Heat transport of the kagomé Heisenberg quantum spin liquid candidate YCu${}_3$(OH)${}_{6.5}$Br${}_{2.5}$: localized magnetic excitations and spin gap

Abstract

The spin-1/2 kagomé Heisenberg antiferromagnet is generally accepted as one of the most promising two-dimensional models to realize a quantum spin liquid state. Previous experimental efforts were almost exclusively on only one archetypal material, the herbertsmithite ZnCu${}_3$(OH)${}_6$Cl${}_2$, which unfortunately suffers from the notorious orphan spins problem caused by magnetic disorders. Here we turn to YCu${}_3$(OH)${}_{6.5}$Br${}_{2.5}$, recently recognized as another host of a globally undistorted kagomé Cu${}^{2+}$ lattice free from the orphan spins, thus a more feasible system for studying the intrinsic kagomé quantum spin liquid physics. Our high-resolution low-temperature thermal conductivity measurements yield a vanishing small residual linear term of $\kappa /T$ ($T\to 0$), and thus clearly rule out itinerant gapless fermionic excitations. Unusual scattering of phonons grows exponentially with temperature, suggesting thermally activated phonon-spin scattering and hence a gapped magnetic excitation, consistent with a ${\mathbb{Z}}_2$ quantum spin liquid ground state. Additionally, the analysis of magnetic field impact on the thermal conductivity reveals a field closing of the spin gap, while the excitations remain localized.

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References in corpus (30)

• Anyons in an exactly solved model and beyond
• Quantum Spin Liquids
• Quantum Spin Liquid States
• Fractionalized excitations in the spin liquid state of a kagomé lattice antiferromagnet
• Quantum Spin Liquids
• Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2
• Identifying Topological Order by Entanglement Entropy
• Projected wavefunction study of Spin-1/2 Heisenberg model on the Kagome lattice
• Herbertsmithite and the Search for the Quantum Spin Liquid
• A Field Guide to Spin Liquids
• Evidence for a Gapped Spin-Liquid Ground State in a Kagome Heisenberg Antiferromagnet
• Gapless spin-liquid phase in the kagome spin-1/2 Heisenberg antiferromagnet
• Disorder-Induced Mimicry of a Spin Liquid in YbMgGaO${}_4$
• Signatures of Dirac cones in a DMRG study of the Kagome Heisenberg model
• Gapless ground state in the archetypal quantum kagome antiferromagnet ZnCu${}_3$(OH)${}_6$Cl${}_2$
• Z2 spin liquid in S=1/2 Heisenberg model on Kagome lattice: A projective symmetry group study of Schwinger-fermion mean-field states
• Gapped spin liquid with ${\mathbb{Z}}_2$-topological order for kagome Heisenberg model
• Emergence of nontrivial magnetic excitations in a spin liquid state of kagome volborthite
• Ultralow-temperature thermal conductivity of the Kitaev honeycomb magnet $\alpha$-RuCl${}_3$ across the field-induced phase transition
• Low-temperature phonon thermal conductivity of cuprate single crystals
• Spin liquids in geometrically perfect triangular antiferromagnets
• Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_x$(OH)${}_{1-x}$]
• Gapless Spin Liquid Behavior in A Kagome Heisenberg Antiferromagnet with Randomly Distributed Hexagons of Alternate Bonds
• Heat transport of cuprate-based low-dimensional quantum magnets with strong exchange coupling
• Heat Transport in Herbertsmithite: Can a Quantum Spin Liquid Survive Disorder?
• Quantum kagome antiferromagnet: ZnCu3(OH)6Cl2
• Presence and absence of itinerant gapless excitations in the quantum spin liquid candidate EtMe${}_3$Sb[Pd(dmit)${}_2$]${}_2$
• Power-law Localization in 2D, 3D with Off-diagonal Disorder
• Field Driven Quantum Criticality in the Spinel Magnet ZnCr${}_2$Se${}_4$
• Thermal transport of the frustrated spin-chain mineral linarite: Magnetic heat transport and strong spin-phonon scattering

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• Magnetic ground states in kagome YCu${}_3$(OH)${}_6$[(Cl${}_x$Br${}_{1-x}$)${}_{3-y}$(OH)${}_y$]
• NMR evidence of spinon localization in kagome antiferromagnet YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_{1-x}$(OH)${}_x$]
• Thermodynamic evidence of fermionic behavior in the vicinity of one-ninth plateau in a kagome antiferromagnet
• Quantum annealing of a frustrated magnet
• 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)${}_{1-x}$]
• 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
• Continuous order-to-order quantum phase transitions from fixed-point annihilation
• Disorder-induced spin-cluster magnetism in a doped kagome spin liquid candidate
• Itinerant and topological excitations in a honeycomb spiral spin liquid candidate
• Exerting chemical pressure on the kagome lattice as frustration control in the kapellasite family $A$Cu${}_3$(OH)${}_{6+x}$(Cl,Br)${}_{3-x}$