Gapless Spin Liquid Behavior in A Kagome Heisenberg Antiferromagnet with Randomly Distributed Hexagons of Alternate Bonds

Abstract

We demonstrate that the new single crystal of YCu${}_3$[OH(D)]${}_{6.5}$Br${}_{2.5}$ (YCOB) is a kagome Heisenberg antiferromagnet (KHA) without evident orphan spins ($\ll$ 0.8\%). The site mixing between polar OH${}^{-}$ and non-polar Br${}^{-}$ causes local distortions of Cu-O-Cu exchange paths, and gives rise to 70(2)\% of randomly distributed hexagons of alternate bonds ($\sim$ $J_1-\Delta J$ and $J_1+\Delta J$) and the rest of almost uniform hexagons ($\sim$ $J_1$) on the kagome lattice. Simulations of the random exchange model with $\Delta J$/$J_1$ = 0.7(1) show good agreement with the experimental observations, including the weak upturn seen in susceptibility and the slight polarization in magnetization. Despite the average antiferromagnetic coupling of $J_1$ $\sim$ 60 K, no conventional freezing is observed down to $T$ $\sim$ 0.001$J_1$, and the raw specific heat exhibits a nearly quadratic temperature dependence below 1 K $\sim$ 0.02$J_1$, phenomenologically consistent with a gapless (spin gap $\le$ 0.025$J_1$) Dirac quantum spin liquid (QSL). Our result sheds new light on the theoretical understanding of the randomness-relevant gapless QSL behavior in YCOB, as well as in other relevant materials.

18 pages, 17 figures

References in corpus (17)

• Non-Abelian Anyons and Topological Quantum Computation
• 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
• 17O NMR study of the intrinsic magnetic susceptibility and spin dynamics of the quantum kagome antiferromagnet ZnCu3(OH)6Cl2
• Dzyaloshinsky-Moriya Anisotropy in the Spin-1/2 Kagomé Compound ZnCu${}_3$(OH)${}_6$Cl${}_2$
• Crystalline Electric Field Randomness in the Triangular Lattice Spin-Liquid YbMgGaO${}_4$
• The magnetic groundstate of an experimental $S=1/2$ kagomé antiferromagnet
• Low temperature magnetization of the S=1/2 kagome antiferromagnet ZnCu_3(OH)_6Cl_2
• Modified kagome physics in the natural spin-1/2 kagome lattice systems - kapellasite Cu3Zn(OH)6Cl2 and haydeeite Cu3Mg(OH)6Cl2
• Spin dynamics and disorder effects in the S=1/2 kagome Heisenberg spin liquid phase of kapellasite
• Dzyaloshinskii-Moriya anisotropy and non-magnetic impurities in the $s=1/2$ kagome system ZnCu_3(OH)_6Cl_2
• Coexistence of magnetic order and persistent spin dynamics in a quantum kagome antiferromagnet with no intersite mixing
• Partial up-up-down order with the continuously distributed order parameter in the triangular antiferromagnet TmMgGaO4
• Local study of the insulating quantum kagome antiferromagnets YCu3(OH)6OxCl3-x (x=0,1/3)
• Kondo screening in a charge-insulating spinon metal
• Field-Induced Instability of a Gapless Spin Liquid with a Spinon Fermi Surface
• Studies of non-magnetic impurities in the spin-1/2 Kagome Antiferromagnet

Cited by in corpus (29)

• Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_x$(OH)${}_{1-x}$]
• Spectral evidence for Dirac spinons in a kagome lattice antiferromagnet
• Heat transport of the kagomé Heisenberg quantum spin liquid candidate YCu${}_3$(OH)${}_{6.5}$Br${}_{2.5}$: localized magnetic excitations and spin gap
• Emergent spin-gapped magnetization plateaus in a spin-1/2 perfect kagome antiferromagnet
• Kitaev Quantum Spin Liquids
• The observation of quantum fluctuations in a kagome Heisenberg antiferromagnet
• Unconventional Magnetic Oscillations in Kagome Mott Insulators
• Magnetic ground states in kagome YCu${}_3$(OH)${}_6$[(Cl${}_x$Br${}_{1-x}$)${}_{3-y}$(OH)${}_y$]
• Nematicity and fractional magnetization plateaus induced by spin-lattice coupling in the classical kagome-lattice Heisenberg antiferromagnet
• Quantum spin liquids of Rydberg excitations in a honeycomb lattice induced by density-dependent Peierls phases
• NMR evidence of spinon localization in kagome antiferromagnet YCu${}_3$(OH)${}_6$Br${}_2$[Br${}_{1-x}$(OH)${}_x$]
• Possible coexistence of short-range resonating-valence-bond and long-range stripe correlations in the spatially anisotropic triangular-lattice quantum magnet Cu${}_2$(OH)${}_3$NO${}_3$
• Thermodynamic evidence of fermionic behavior in the vicinity of one-ninth plateau in a kagome antiferromagnet
• Spiral spin liquid in a frustrated honeycomb antiferromagnet: A single-crystal study of GdZnPO
• Quantum annealing of a frustrated magnet
• Interplay between multi-spin and chiral spin interactions on triangular lattice
• Schwinger boson study of the $J_1$-$J_2$-$J_3$ kagome Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions
• 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)${}_{0.67}$]
• Proximate Tomonaga-Luttinger liquid in a spin-1/2 ferromagnetic XXZ chain compound
• Recent progress in quantum spin liquids, fractional magnetization plateaus, and unconventional superconductivity in kagome lattices
• Exerting chemical pressure on the kagome lattice as frustration control in the kapellasite family $A$Cu${}_3$(OH)${}_{6+x}$(Cl,Br)${}_{3-x}$
• Itinerant and topological excitations in a honeycomb spiral spin liquid candidate
• Disorder-induced spin-cluster magnetism in a doped kagome spin liquid candidate
• An integrated theoretical and numerical approach to understand modern experiments on quantum magnetism
• Spin Liquid Mimicry in the Hydroxide Double Perovskite CuSn(OH)${}_6$ Induced by Correlated Proton Disorder
• Emergence of a Fluctuating Ground State in Y-kapellasite under Pressure
• Universal collective Larmor-Silin mode emerging in magnetized correlated Dirac fermions
• Dynamical Spectral Function of the Kagome Quantum Spin Liquid