A high-temperature quantum spin liquid with polaron spins


The existence of a quantum spin liquid (QSL) in which quantum fluctuations of spins are sufficiently strong to preclude spin ordering down to zero temperature was originally proposed theoretically more than 40 years ago, but its experimental realization turned out to be very elusive. Here we report on an almost ideal spin liquid state that appears to be realized by atomic-cluster spins on the triangular lattice of a charge-density wave state of 1T-TaS2. In this system, the charge excitations have a well-defined gap of 0.3 eV, while nuclear quadrupole resonance and muon-spin-relaxation experiments reveal that the spins show gapless QSL dynamics and no long-range magnetic order at least down to 70 mK. Canonical T2 power-law temperature dependence of the spin relaxation dynamics characteristic of a QSL is observed from 200 K to Tf = 55 K. Below this temperature, we observe a new gapless state with reduced density of spin excitations and high degree of local disorder signifying new quantum spin order emerging from the QSL.

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Figure 1: μ+SR rules out any long-range magnetic order down to 70 mK.
Figure 2: 181Ta NQR spectrum reveals the symmetry and the structure of deformations in the Star-of-David Ta cluster.
Figure 3: 181Ta relaxation rates probe the quantum spin liquid.
Figure 4: The low-temperature state of 1T-TaS2.


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The authors acknowledge fruitful discussions with P. Carretta. The authors also acknowledge the contribution of P. Šutar in sample preparation and structural characterization. D.A. acknowledges the financial support by the Slovenian Research Agency, grant No. N1-0052; D.M. acknowledges funding by the ERC AdG Trajectory.

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D.A., D.M. and P.P. conceived and designed the project and directed and coordinated the research. M.K., A.Z. and P.K.B. performed the μ+SR experiments and analysed the data. M.K. and A.Z. carried out NQR measurements and analysed the data. Z.J. measured spin susceptibility and together with D.A. analysed the data. All authors discussed the results. D.A. wrote the paper with input from all authors.

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Correspondence to Denis Arčon.

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Klanjšek, M., Zorko, A., Žitko, R. et al. A high-temperature quantum spin liquid with polaron spins. Nature Phys 13, 1130–1134 (2017). https://doi.org/10.1038/nphys4212

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