Local measurement of the superfluid density in the pnictide superconductor Ba(Fe(1-x)Co(x))(2)As(2) across the superconducting dome

Phys Rev Lett. 2011 Feb 11;106(6):067001. doi: 10.1103/PhysRevLett.106.067001. Epub 2011 Feb 9.

Abstract

We measure the penetration depth λab(T) in Ba(Fe(1-x)Co(x))(2)As(2) using local techniques that do not average over the sample. The superfluid density ρs(T) ≡ 1/λab(T)2 has three main features. First, ρs (T = 0) falls sharply on the underdoped side of the dome. Second, λab(T) is flat at low T at optimal doping, indicating fully gapped superconductivity, but varies more strongly in underdoped and overdoped samples, consistent with either a power law or a small second gap. Third, ρs (T) varies steeply near Tc for optimal and underdoping. These observations are consistent with an interplay between magnetic and superconducting phases.

MeSH terms

  • Arsenic / chemistry*
  • Barium / chemistry*
  • Cobalt / chemistry*
  • Iron / chemistry*
  • Temperature

Substances

  • Barium
  • Cobalt
  • Iron
  • Arsenic