Effect of heavy-ion irradiation on London penetration depth in overdoped Ba(Fe1-xCox)(2)As-2
Brooks, J. S.
Irradiation with 1.4 GeV 208Pb ions was used to induce artificial disorder in single crystals of iron-arsenide superconductor Ba(Fe1−xCox)2As2 and to study its effects on the temperature-dependent London penetration depth and transport properties. A study was undertaken on overdoped single crystals with x=0.108 and x=0.127 characterized by notable modulation of the superconducting gap. Irradiation corresponding to the matching fields of Bϕ=6 T and 6.5 T with doses 2.22×1011 d/cm2 and 2.4×1011 d/cm2, respectively, suppresses the superconducting Tc by approximately 0.3 to 1 K. The variation of the low-temperature penetration depth in both pristine and irradiated samples is well described by the power law Δλ(T)=ATn. Irradiation increases the magnitude of the prefactor A and decreases the exponent n, similar to the effect of irradiation in optimally-doped samples. This finding supports universal s± pairing in Ba(Fe1−xCox)2As2 compounds for the entire Co doping range.
This article is published as Murphy, J., M. A. Tanatar, Hyunsoo Kim, W. Kwok, U. Welp, D. Graf, J. S. Brooks, S. L. Bud'ko, P. C. Canfield, and R. Prozorov. "Effect of heavy-ion irradiation on London penetration depth in overdoped Ba (Fe 1− x Co x) 2 As 2." Physical Review B 88, no. 5 (2013): 054514. DOI: 10.1103/PhysRevB.88.054514. Posted with permission.