Evidence of a Normal-State Pseudogap in Bulk Superconducting Tunneling Junctions of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub>

  • Leandro Guerra
  • Mildred Reyes
  • Ayn Manuel
  • Roland Sarmago
  • Arnel Salvador

Abstract

Planar contact tunneling experiments have been performed on bulk superconducting tunneling junctions of YBa2Cu3O7-δ in the temperature range 77 -295K. A clear depression in the conductance curves measured, attributed to the pseudogap, has been observed in temperatures above Tc (approx. 90K determined from dc resistivity measurements) before disappearing at T*=275K. The width of the pseudogap has been quantitatively measured as Dps, ave = 25.6meV from the differential conductance plots. These results agree with the current understanding of the phenomenology and nature of this pseudogap, namely: (I) the pseudogap value is relatively temperature-independent; (2) the superconducting gap and the pseudogap have the same d-wave nature; and (3) the superconducting gap evolves from the pseudogap.
Published
2007-09-14
Section
Articles

Keywords

Pseudogap; tunneling; YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub>