Spinon mediation of witness spin dynamics in herbertsmithite
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Date
2026-06-10
Authors
Takahashi, Hiroto
Murphy, Jack
Wood-Thanan, Mitikorn
Puphal, Pascal
Sánchez-Martínez, Miguel Ángel
Jerzembeck, Fabian
Hsu, Chun Chih
Ward, Jonathan
Isobe, Masahiko
Matsumoto, Yosuke
Journal Title
Journal ISSN
Volume Title
Publisher
Nature Research
Published Version
Abstract
The kagome lattice of spin-1/2 copper atoms in herbertsmithite is conjectured to sustain a quantum spin liquid state with spinon quasiparticles. Ideally, the kagome crystal planes are each separated by a plane of spinless zinc atoms. However, in real crystals, some spin-1/2 copper atoms substitute randomly onto these inter-kagome zinc sites. Here we reconceptualize such ‘impurity’ atoms as quantum witness spins whose dynamics is designed to probe the spin liquid state. We then introduce spin noise spectroscopy to measure the frequency and temperature dependence of witness spin dynamics, demonstrating that their phenomenology is consistent with extensive interactions between witness spins mediated by propagation of spinons through a quantum spin liquid. Ultimately, a sharp transition occurs at around 260 mK, below which the properties of both spin noise and magnetic susceptibility suggest that the witness spins form a spin glass phase. Among the theoretical models considered, we demonstrate that our observations are only consistent with spinon-mediated interactions between witness spins by either a Z2 or U(1) quantum spin liquid, with the former model more closely matching the data. Our work demonstrates that quantum mechanical witness spins may now conceivably be used as a widely applicable probe of quantum spin liquid physics.
Description
Keywords
Kagome lattice , Spin-1/2 copper atoms , Spinon mediation , Spin dynamics , Herbertsmithite , [Physics]
Citation
Takahashi, H, Murphy, J, Wood-Thanan, M, Puphal, P, Sánchez-Martínez, M Á, Jerzembeck, F, Hsu, C C, Ward, J, Isobe, M, Matsumoto, Y, Takagi, H, Blundell, S J, Norman, M R, Flicker, F & Davis, J C S 2026, 'Spinon mediation of witness spin dynamics in herbertsmithite', Nature Physics, vol. 22, no. 7, pp. 1071-1078. https://doi.org/10.1038/s41567-026-03303-6