paper

London penetration depth in Ba(Fe $_{1 - x}$ T $_{x}$ ) $_{2}$ As $_{2}$ (T=Co, Ni) superconductors irradiated with heavy ions

arXiv:1003.2959 · doi:10.1103/PhysRevB.82.060518

Abstract

Irradiation with Pb ions was used to study the effect of disorder on the in-plane London penetration depth, $I^» (T)$ , in single crystals of Ba(Fe $_{1 - x}$ T $_{x}$ ) $_{2}$ As $_{2}$ (T=Co, Ni). An increase of the irradiation dose results in a monotonic decrease of the superconducting transition temperature, $T_{c}$ , without affecting much the transition width. In both Co and Ni doped systems we find a power-law behavior, $I^ I^» (T) \propto T^{n}$ , with the exponent $n$ systematically decreasing with the increase of disorder. This observation, supported by the theoretical analysis, conclusively points to a nodeless $s^{\pm}$ state with pairbreaking impurity scattering (interband) with strength being intermediate between Born and unitary limits.

new version includes theoretical model

London penetration depth in Ba(Fe1−x​Tx​)2​As2​ (T=Co, Ni) superconductors irradiated with heavy ions

Abstract

London penetration depth in Ba(Fe $_{1 - x}$ T $_{x}$ ) $_{2}$ As $_{2}$ (T=Co, Ni) superconductors irradiated with heavy ions