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Chung-Hou CHUNG (1 Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan – 2 Physics Division, National center for Theoretical Sciences, Taipei,Taiwan)

13 octobre @ 14:00

A theory for quantum-critical Planckian strange metal phase in high-Tc cuprate superconductors

Résumé :

The strange metallic state showing incoherent charge transport with universal linear-in-temperature scattering rate: 1/τ = αP kB T / ħ with αP ~ 1 and logarithmic-in-temperature singular specific heat coefficient, so-called “Planckian metal”, has been observed in various high-Tc cuprate superconductors over a finite range in doping near optimal doping [1]. Understanding this state is believed to be the key to revealing the mechanism for high-Tc superconductivity. Here, we propose a generic microscopic mechanism for this state based on quantum-critical local bosonic charge Kondo fluctuations coupled to both spinon and a heavy conduction-electron Fermi surfaces within the heavy-fermion formulated slave-boson t-J model [2]. Our theory is motivated by the striking similarity in strange metal phenomenology between cuprates and heavy-fermion Kondo lattice systems [3]. By a controlled perturbative renormalization group analysis of our effective heavy-fermion model, we examine the competition between the pseudogap phase, characterized by Anderson’s Resonating-Valence-Bond spin-liquid made of fermionic spin-singlet spinons, and the Fermi-liquid state modeled by coherent electron hopping (charge Kondo hybridization). We find an extended quantum-critical metallic phase with a universal Planckian ħω/kBT scaling in scattering rate near a localized-delocalized (pseudogap-to-Fermi liquid) charge-Kondo breakdown transition of the model. The d-wave superconducting ground state emerges near the transition. Unprecedented qualitative and quantitative agreements are reached between our theoretical predictions and various experiments, including ħω/kBT scaling in optical conductivity [4], universal doping-insensitive field-to-temperature (B/T-) scaling in magnetoresistance [5], singular specific heat coefficient [6], marginal Fermi-liquid spectral function observed in ARPES [7], and Fermi surface reconstruction observed in Hall coefficients in various overdoped cuprates [5,8]. We further applied this framework to obtain a universal quantum-critical B/T-scaling in magneto-transport and unify the B-linear and T-linear Planckian scattering rate observed in LSCO over an extended doping range, pointing toward a unified quantum–critical origin of Planckian transport in cuprates [9]. This universal Planckian metal phase can be realized within a solvable large-N multi-channel Kondo lattice model generalized from this heavy-fermion formulated tJ model [10]. Our mechanism offers a microscopic understanding of the quantum-critical Planckian metal phase observed in cuprates and its link to the pseudogap, d-wave superconducting, and Fermi liquid phases. It offers a promising route for understanding how d-wave superconductivity emerges from such a strange metal phase in cuprates–one of the long-standing open problems in condensed matter physics since 1990s.

References

  1. Legros et al., Nat. Phys. 15, 142 (2019).
  2. A mechanism for quantum-critical Planckian metal phase in high-temperature cuprate superconductors, YY Chang, K Van Nguyen, K Remund, C.H. Chung*, Reports on Progress in Physics, 88, 048001 (2025).
  3. The scaled-invariant Planckian metal and quantum criticality in Ce1-xNdxCoIn5, Yung-Yeh Chang, Hechang Lei, Cedomir Petrovic*, Chung-Hou Chung*, Nature Communications 14 (581) (2023); A mechanism for the strange metal phase in rare-earth intermetallic compounds”, Jiangfan Wang, Yung-Yeh Chang and Chung-Hou Chung*, Proceedings of the National Academy of Sciences (PNAS), Volume 119(10) e2116980119 March 1, 2022; Strange superconductivity near an antiferromagnetic heavy fermion quantum critical point, Y. Y. Chang, F. Hsu, S. Kirchner, C. Y. Mou, T. K. Lee, C. H. Chung*, Phys. Rev. B 99, 094513 (2019); Mechanism of a strange metal state near a heavy-fermion quantum critical point, Yung-Yeh Chang, Silke Paschen, Chung-Hou Chung*, Phys. Rev. B 97, 035156 (2018).
  4. B. Michon et al., Nature Communications 14, 3033 (2023).
  5. J. Ayres et al., Nature 595, 661 (2021).
  6. B. Michon et al., Nature 567, 218 (2019).
  7. S.D. Chen et al., Science, 366, 1099 (2019).
  8. C. Proust et al., Annual Review of Condensed Matter Physics 10, 409 (2019).
  9. Universality of T –linear and B–linear Planckian scattering rate in high–Tc cuprate superconductors, K. Remund, K. V. Nguyen, P.-H. Chou, P. Giraldo-Gallo, J. A. Galvis, G. S. Boebinger, and C.-H. Chung*, arXiv:2602.10627.
  10. Theory of universal Planckian metal phase in t-J model: application for high-temperature cuprate superconductors, YY Chang, K Van Nguyen, K Remund, CH Chung*, arXiv:2506.15552

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Contact : david.leboeuf@lncmi.cnrs.fr

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