Normal state specific heat in the cuprate superconductors La2-xSrxCuO4 and Bi2+ySr2-x-yLaxCuO6+δ near the critical point of the pseudogap phase

C. Girod, D. Leboeuf, A. Demuer, G. Seyfarth, S. Imajo, K. Kindo, Y. Kohama, M. Lizaire, A. Legros, A. Gourgout, H. Takagi, T. Kurosawa, M. Oda, N. Momono, J. Chang, S. Ono, G. Q. Zheng, C. Marcenat, L. Taillefer, T. Klein

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2 Citations (Scopus)

Abstract

The specific heat C of the cuprate superconductors La2-xSrxCuO4 and Bi2+ySr2-x-yLaxCuO6+δ was measured at low temperatures (down to 0.5 K) for dopings p close to p∗, the critical doping for the onset of the pseudogap phase. A magnetic field up to 35 T was applied to suppress superconductivity, giving direct access to the normal state at low temperatures, and enabling a determination of Ce, the electronic contribution to the normal-state specific heat at T→0. In La2-xSrxCuO4 at x=p=0.22, 0.24 and 0.25, Ce/T=15to16mJmol-1K-2 at T=2K, values that are twice as large as those measured at higher doping (p>0.3) and lower doping (p<0.15). This confirms the presence of a broad peak in the doping dependence of Ce at p∗≃0.19 as previously reported for samples in which superconductivity was destroyed by Zn impurities. Moreover, at those three dopings, we find a logarithmic growth as T→0 such that Ce/T∼Bln(T0/T). The peak versus p and the logarithmic dependence versus T are the two typical thermodynamic signatures of quantum criticality. In the very different cuprate Bi2+ySr2-x-yLaxCuO6+δ, we again find that Ce/T∼Bln(T0/T) at p≃p∗, strong evidence that this ln(1/T) dependence of the electronic specific heat - first discovered in the cuprates La1.8-xEu0.2SrxCuO4 and La1.6-xNd0.4SrxCuO4 - is a universal property of the pseudogap critical point.

Original languageEnglish
Article number214506
JournalPhysical Review B
Volume103
Issue number21
DOIs
Publication statusPublished - Jun 1 2021

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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