Agreement between local and global measurements of the London   penetration depth
  Recent measurements of the superconducting penetration depth in Ba(Fe_1-x Co_x)2As2 appeared to disagree on the magnitude and curvature of {\Delta}{\lambda}_{ab}(T), even near optimal doping. These measurements were carried out on different samples grown by different groups. To understand the discrepancy, we use scanning SQUID susceptometry and a tunnel diode resonator to measure the penetration depth in a single sample. The penetration depth observed by the two techniques is identical with no adjustments. We conclude that any discrepancies arise from differences between samples, either in growth or crystal preparation. 
Thomas M. Lippman, Beena Kalisky, Hyunsoo Kim, Makariy A. Tanatar,   Sergey L. Bud'ko, Paul C. Canfield, Ruslan Prozorov, Ka...
cond-mat.supr-con