Source capture
Authors C. Iorio-Duval, E. Beauchesne-Blanchet, F. Perreault, J. L. Santana González, S. Üstün Kaykusuz, W. Sun, D. Graf, Y. F. Nie, A. Gourgout, G. Grissonnanche
arXiv / Publisher https://arxiv.org/abs/2510.12786
PDF https://arxiv.org/pdf/2510.12786
Relevance score 4.908
Primary category cond-mat.str-el
Published 2026-07-21
Research paradigm Not available in this batch.
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Summary

Infinite-layer nickelate superconductors provide a new platform to study the quantum critical origin of strange metals, yet their thin-film form forbids conventional calorimetry. Using the Seebeck coefficient as a proxy for low-temperature specific heat, we find at the critical doping x* that the high-temperature Seebeck response quantitatively matches the band structure measured by ARPES, indicating well-defined quasiparticles, while below 60 K, S/T develops a logarithmic divergence that persists to the lowest temperatures (after suppressing superconductivity with a magnetic field), marking x* as a quantum critical point that terminates the underdoped phase. Moreover, the Ni-dx2-y2 carrier density drops abruptly from 1+x above x* to x below x*, reproducing the hallmark signature of the pseudogap phase in cuprates. These results indicate that the underdoped region of infinite-layer nickelates is a pseudogap-like state, at whose end emergent strange metal behavior with T-linear resistivity provides strong evidence for a quantum critical origin of strange metals.

Materials

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Methods

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Keywords

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Highlights

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Conclusions

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Main claims

  • At doping x*, the low-temperature Seebeck coefficient (S/T) exhibits a logarithmic divergence persisting after suppression of superconductivity, marking x* as a quantum critical point.
    • Evidence: Seebeck measurements show S/T ∝ log(T) below 60 K at x* (Fig. 2a),No divergence at neighboring dopings (x=0.06, 0.38),Superconductivity suppressed with B=41.5T
  • Above 60 K, the high-temperature Seebeck response at x* is quantitatively reproduced by ARPES band structure calculations, indicating well-defined quasiparticles.
    • Evidence: Boltzmann transport calculation based on ARPES dispersion matches measured S magnitude and sign (Fig. 2b)
  • The carrier density of the Ni-dx2-y2 band drops from 1+x to x across x*, analogous to the pseudogap carrier loss in cuprates.
    • Evidence: Two-band analysis of Hall coefficient data from Lee et al. (2023) shows abrupt drop at x*,Hall coefficient sign change from positive to negative

Workflow

  • measurement
    • Materials: La1-xSrxNiO2 thin films
    • Methods: Seebeck coefficient measurements as function of temperature and doping; suppression of superconductivity using B=41.5 T magnetic field
    • Observations: Above 60 K, S is constant and negative; below 60 K, S/T diverges logarithmically at x*; No logarithmic divergence at neighboring dopings (x=0.06, 0.38); Superconductivity suppressed to reveal normal-state divergence
  • analysis
    • Materials: ARPES band structure data from prior work; Hall coefficient data from Lee et al.
    • Methods: Boltzmann transport calculation to compute S from ARPES dispersion; Two-band model fit to zero-temperature Hall coefficient to extract Ni-d carrier density
    • Observations: Computed S matches measured S in sign and magnitude above 60K; Ni-d carrier density n_d drops from 1+x to x across x*
  • interpretation — The doping x* is a quantum critical point terminating a pseudogap-like phase, from which strange metal behavior (T-linear resistivity) emerges; analogies with cuprates established.