Thermodynamic signatures of quantum criticality in cuprate superconductors Academic Article uri icon

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  • The three central phenomena of cuprate (copper oxide) superconductors are linked by a common doping level p*-at which the enigmatic pseudogap phase ends and the resistivity exhibits an anomalous linear dependence on temperature, and around which the superconducting phase forms a dome-shaped area in the phase diagram1. However, the fundamental nature of p* remains unclear, in particular regarding whether it marks a true quantum phase transition. Here we measure the specific heat C of the cuprates Eu-LSCO and Nd-LSCO at low temperature in magnetic fields large enough to suppress superconductivity, over a wide doping range2 that includes p*. As a function of doping, we find that Cel/T is strongly peaked at p* (where Cel is the electronic contribution to C) and exhibits a log(1/T) dependence as temperature T tends to zero. These are the classic thermodynamic signatures of a quantum critical point3-5, as observed in heavy-fermion6 and iron-based7 superconductors at the point where their antiferromagnetic phase comes to an end. We conclude that the pseudogap phase of cuprates ends at a quantum critical point, the associated fluctuations of which are probably involved in d-wave pairing and the anomalous scattering of charge carriers.


  • Michon, B
  • Girod, C
  • Badoux, S
  • Kačmarčík, J
  • Ma, Q
  • Dragomir, M
  • Dabkowska, Hanna
  • Gaulin, Bruce D
  • Zhou, J-S
  • Pyon, S
  • Takayama, T
  • Takagi, H
  • Verret, S
  • Doiron-Leyraud, N
  • Marcenat, C
  • Taillefer, L
  • Klein, T

publication date

  • March 2019