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arXiv · 2504.06491

Identifying Universal Spin Excitations in 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
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Abstract

A quantum spin liquid (QSL) is an exotic quantum state of matter characterized by fluctuating spins which may exhibit long-range entanglement. Among the possible host candidates for a QSL ground state, the $S$=1/2 kagome lattice antiferromagnet is particularly promising. Using high resolution inelastic neutron scattering measurements on Zn-barlowite (Zn$_\mathrm{x}$Cu$_\mathrm{4-x}$(OD)$_\mathrm{6}$FBr, $x\simeq 0.80$), we measure a spin excitation spectrum consistent with a QSL ground state. Continuum scattering above $\sim$1 meV matches that of herbertsmithite (Zn$_\mathrm{x}$Cu$_\mathrm{4-x}$(OD)$_6$Cl$_2$, $x\simeq 0.85$), another prominent kagome QSL material, indicating universal spinon excitations. A detailed analysis of the spin-spin correlations, compared with density matrix renormalization group calculations, further indicate a QSL ground state for the physically relevant Hamiltonian parameters. The measured spectra in Zn-barlowite are consistent with gapped behavior with a gap size $\Delta = 1.1(2)$ meV. Comparison with a simple pair correlation model allows us to clearly distinguish intrinsic kagome correlations from impurity-induced correlations. Our results clarify the behavior that is universal within this important family of QSL candidate materials.

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Aaron T. Breidenbach, Arthur C. Campello, Jiajia Wen, Hong-Chen Jiang, Daniel M. Pajerowski, Rebecca W. Smaha, Young S. Lee. 2025-04-08. Identifying Universal Spin Excitations in Spin-1/2 Kagome Quantum Spin Liquid Materials. https://arxiv.org/abs/2504.06491

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