2011/05/11 by H. Kim, M. A. Tanatar, Kim, H. +7
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Iron-based superconductors research #Rare-earth and actinide compounds #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.1105.2265
openalex publication_date 2011/05/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The in-plane London penetration depth, Δλ(T), was measured using a tunnel diode resonator in single crystals of Ba1-xKxFe2As2 for five doping levels x ranging from underdoped, Tc=11 K (x=0.17), to optimally doped, Tc=38 K (x_\textmd\scriptsize opt= 0.35). In the optimally doped samples, Δλ(T) shows exponential saturation in T → 0 limit suggesting a fully gapped superconductivity. The lowest-Tc samples show much stronger non-exponential variation of Δλ(T). Fitting the data to a power-law, Δλ(T)= ATn, reveals a monotonic decrease of the exponent n with x towards the underdoped edge of the superconducting dome. Comparison with n ≈ 1.2 reported in KFe2As2 (Tc=3.5 K, x= 1), suggests a dome-like variation of n with x, implying an evolution of the topology of the superconducting gap from full and isotropic in the center of the dome towards strongly anisotropic and, eventually, nodal at the dome edges.