Abstract
Overdoped cuprate superconductors are strange metals above their superconducting transition temperature. In such materials, the electrical resistivity has a strong linear dependence on temperature (T) and electrical current is not carried by electron quasiparticles as in conventional metals. Here we demonstrate that the strange metal behaviour co-exists with strongly temperature-dependent critical spin fluctuations showing dynamical scaling across the cuprate phase diagram. Our neutron scattering observations and the strange metal behaviour are consistent with a spin density wave quantum phase transition in a metal with spatial disorder in the tuning parameter. Numerical computations using a theory of spin density waves in a disordered metal yield an extended ‘Griffiths phase’ with scaling properties in agreement with experimental observations. Thus we establish that low-energy spin excitations and spatial disorder are central to the strange metal behaviour.
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Source data for experimental figures are provided at https://doi.org/10.5281/zenodo.18682259. Raw data are at https://doi.org/10.5286/ISIS.E.RB2220248-1 and https://doi.org/10.5286/ISIS.E.RB2410260-1.
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Acknowledgements
S.M.H. is grateful to Jörg Schmalian for sharing insights about scaling theory. A.A.P. and S.S. thank Peter Lunts for related collaborations. Neutron beamtime was provided by the ISIS neutron and muon source through proposals RB2220248 and RB2410260. Work was supported by the U.K. EPSRC through grant EP/R011141/1. The Flatiron Institute is a division of the Simons Foundation. S.S. was supported by the U.S. National Science Foundation grant No. DMR-2245246.
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Single crystals were grown and characterised by O.J.L and S.M.H. Neutron scattering measurements were performed by J.R., M.Z., J.R.S., and S.M.H. Data analysis performed by J.R. and S.M.H. Numerical theory performed by A.A.P. and S.S. The paper was written by J.R., A.A.P., S.S., and S.M.H.
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Radaelli, J., Patel, A.A., Zhu, M. et al. Critical spin fluctuations across the superconducting dome in La2−xSrxCuO4. Nat Commun (2026). https://doi.org/10.1038/s41467-026-71319-w
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DOI: https://doi.org/10.1038/s41467-026-71319-w
