Materials Science and Engineering, Physics and Astronomy, Ames Laboratory
Journal or Book Title
Physical Review B
London penetration depth, lambda(T), was measured in single crystals of K1-xNaxFe2As2, x = 0 and 0.07, down to temperatures of 50 mK, similar to T-c/50. Isovalent substitution of Na for K significantly increases impurity scattering, with rho(T-c) rising from 0.2 to 2.2 mu Omega 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 Delta lambda(T) in pure samples changes to almost T-2 in the substituted samples. The behavior never becomes exponential as expected for the accidental nodes, as opposed to T-2 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.
American Physical Society
Kim, H.; Tanatar, Makariy A.; Liu, Yong; Sims, Zachary Cole; Zhang, Chenglin; Dai, Pengcheng; Lograsso, Thomas A.; and Prozorov, Ruslan, "Evolution of London penetration depth with scattering in single crystals of K1-xNaxFe2As2" (2014). Ames Laboratory Publications. 425.