Evolution of London Penetration Depth with Scattering in Single Crystals of Ba₁₋ₓNaₓFe₂As₂

Author

Hyunsoo Kim, Missouri University of Science and TechnologyFollow
M. A. Tanatar
Yong Liu
Zachary Cole Sims
Chenglin Zhang
Pengcheng Dai
T. A. Lograsso
R. Prozorov

Abstract

London penetration depth, λ(T), was measured in single crystals ofK_1-xNa_xFe₂As₂, x = 0 and 0.07, down to temperatures of 50 mK, ~ T_c/50. Isovalent substitution of Na for K significantly increases impurity scattering, with ρ(T_c) rising from 0.2 to 2.2 µΩ cm, and leads to a suppression of T_c from 3.5 to 2.8 K. At the same time, a close to T-linear Δλ(T) in pure samples changes to almost T² in the substituted samples. The behavior never becomes exponential as expected for the accidental nodes, as opposed to T² dependence in superconductors with symmetry imposed line nodes. The superfluid density in the full temperature range follows a simple clean and dirty d-wave dependence, for pure and substituted samples, respectively. This result contradicts suggestions of multiband scenarios with strongly different gap structure on four sheets of the Fermi surface.

Recommended Citation

H. Kim et al., "Evolution of London Penetration Depth with Scattering in Single Crystals of Ba₁₋ₓNaₓFe₂As₂," Physical Review B - Condensed Matter and Materials Physics, vol. 89, no. 17, article no. 174519, American Physical Society (APS), May 2014.

The definitive version is available at https://doi.org/10.1103/PhysRevB.89.174519

Department(s)

Physics

International Standard Serial Number (ISSN)

1550-235X; 1098-0121

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2014 American Physical Society (APS), All rights reserved.

Publication Date

30 May 2014