Temperature-dependent London penetration depth λ(T) was measured in optimally doped x=0.35, as-grown [Tc≈25 K, RRR=ρ(300K)/ ρ(Tc)=4.5], and annealed (Tc≈35 K, RRR=6.4) single crystals of SrFe2(As1-xPx)2 iron-based superconductor. Annealing increases the residual resistivity ratio (RRR) and decreases the absolute value of the London penetration depth from λ(0)=300±10 nm in the as-grown sample to λ(0)=275±10 nm. At low temperatures, λ(T)∼T indicating a superconducting gap with line nodes. Analysis of the full-temperature range superfluid density is consistent with the line nodes, but differs from the simple single-gap d wave. The observed behavior is very similar to that of BaFe2(As 1-xPx)2, showing that isovalently substituted pnictides are inherently different from the charge-doped materials.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Apr 16 2013|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics