Identifying universal spin excitations in candidate spin-1/2 kagome quantum spin liquid materials

Aaron T. Breidenbach; Arthur C. Campello; Jiajia Wen; Hong Chen Jiang; Daniel M. Pajerowski; Rebecca W. Smaha; Young S. Lee

doi:10.1038/s41567-025-03069-3

Identifying universal spin excitations in candidate spin-1/2 kagome quantum spin liquid materials

Aaron T. Breidenbach
, Arthur C. Campello
, Jiajia Wen
, Hong Chen Jiang
, Daniel M. Pajerowski
, Rebecca W. Smaha
, Young S. Lee

Direct Geometry

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

A quantum spin liquid is an exotic quantum state of matter characterized by fluctuating spins that may exhibit long-range entanglement. Among the possible host candidates for a quantum spin liquid ground state, the S = 1/2 kagome lattice antiferromagnet is particularly promising. Here we measure a spin excitation spectrum consistent with a quantum spin liquid using high-resolution inelastic neutron scattering measurements on Zn-barlowite (Zn_xCu_4−x(OD)₆FBr, x ≃ 0.80). We observe continuum scattering that matches earlier observations in herbertsmithite (Zn_xCu_4−x(OD)₆Cl₂, x ≃ 0.85), another prominent kagome quantum spin liquid candidate, which could represent a universal scattering process from spinon excitations. A detailed analysis of the spin–spin correlations, compared with density matrix renormalization group calculations with physically relevant Hamiltonian parameters, further indicates that the ground state is a quantum spin liquid. The measured spectra in Zn-barlowite are consistent with gapped behaviour. Comparison with a simple pair correlation model allows us to clearly distinguish intrinsic kagome correlations from impurity-induced correlations. Our results identify potential universal behaviour within this important family of quantum spin liquid candidate materials.

Original language	English
Pages (from-to)	1957-1964
Number of pages	8
Journal	Nature Physics
Volume	21
Issue number	12
DOIs	https://doi.org/10.1038/s41567-025-03069-3
State	Published - Dec 2025

Funding

We thank S. Kivelson and W. He for insightful discussions. We thank R. Matheu for assistance in collecting the crystallography data. We thank D. Burns for assistance with the electron microprobe measurements. This work is supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under contract number DE-AC02-76SF00515. This research used resources at the Spallation Neutron Source, US DOE, Office of Science User Facilities, operated by the Oak Ridge National Laboratory. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award number ECCS-2026822. R.W.S. was supported by an NSF Graduate Research Fellowship (DGE-1656518).

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title = "Identifying universal spin excitations in candidate spin-1/2 kagome quantum spin liquid materials",

abstract = "A quantum spin liquid is an exotic quantum state of matter characterized by fluctuating spins that may exhibit long-range entanglement. Among the possible host candidates for a quantum spin liquid ground state, the S = 1/2 kagome lattice antiferromagnet is particularly promising. Here we measure a spin excitation spectrum consistent with a quantum spin liquid using high-resolution inelastic neutron scattering measurements on Zn-barlowite (ZnxCu4−x(OD)6FBr, x ≃ 0.80). We observe continuum scattering that matches earlier observations in herbertsmithite (ZnxCu4−x(OD)6Cl2, x ≃ 0.85), another prominent kagome quantum spin liquid candidate, which could represent a universal scattering process from spinon excitations. A detailed analysis of the spin–spin correlations, compared with density matrix renormalization group calculations with physically relevant Hamiltonian parameters, further indicates that the ground state is a quantum spin liquid. The measured spectra in Zn-barlowite are consistent with gapped behaviour. Comparison with a simple pair correlation model allows us to clearly distinguish intrinsic kagome correlations from impurity-induced correlations. Our results identify potential universal behaviour within this important family of quantum spin liquid candidate materials.",

author = "Breidenbach, \{Aaron T.\} and Campello, \{Arthur C.\} and Jiajia Wen and Jiang, \{Hong Chen\} and Pajerowski, \{Daniel M.\} and Smaha, \{Rebecca W.\} and Lee, \{Young S.\}",

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AU - Pajerowski, Daniel M.

AU - Smaha, Rebecca W.

AU - Lee, Young S.

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N2 - A quantum spin liquid is an exotic quantum state of matter characterized by fluctuating spins that may exhibit long-range entanglement. Among the possible host candidates for a quantum spin liquid ground state, the S = 1/2 kagome lattice antiferromagnet is particularly promising. Here we measure a spin excitation spectrum consistent with a quantum spin liquid using high-resolution inelastic neutron scattering measurements on Zn-barlowite (ZnxCu4−x(OD)6FBr, x ≃ 0.80). We observe continuum scattering that matches earlier observations in herbertsmithite (ZnxCu4−x(OD)6Cl2, x ≃ 0.85), another prominent kagome quantum spin liquid candidate, which could represent a universal scattering process from spinon excitations. A detailed analysis of the spin–spin correlations, compared with density matrix renormalization group calculations with physically relevant Hamiltonian parameters, further indicates that the ground state is a quantum spin liquid. The measured spectra in Zn-barlowite are consistent with gapped behaviour. Comparison with a simple pair correlation model allows us to clearly distinguish intrinsic kagome correlations from impurity-induced correlations. Our results identify potential universal behaviour within this important family of quantum spin liquid candidate materials.

AB - A quantum spin liquid is an exotic quantum state of matter characterized by fluctuating spins that may exhibit long-range entanglement. Among the possible host candidates for a quantum spin liquid ground state, the S = 1/2 kagome lattice antiferromagnet is particularly promising. Here we measure a spin excitation spectrum consistent with a quantum spin liquid using high-resolution inelastic neutron scattering measurements on Zn-barlowite (ZnxCu4−x(OD)6FBr, x ≃ 0.80). We observe continuum scattering that matches earlier observations in herbertsmithite (ZnxCu4−x(OD)6Cl2, x ≃ 0.85), another prominent kagome quantum spin liquid candidate, which could represent a universal scattering process from spinon excitations. A detailed analysis of the spin–spin correlations, compared with density matrix renormalization group calculations with physically relevant Hamiltonian parameters, further indicates that the ground state is a quantum spin liquid. The measured spectra in Zn-barlowite are consistent with gapped behaviour. Comparison with a simple pair correlation model allows us to clearly distinguish intrinsic kagome correlations from impurity-induced correlations. Our results identify potential universal behaviour within this important family of quantum spin liquid candidate materials.

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Identifying universal spin excitations in candidate spin-1/2 kagome quantum spin liquid materials

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