Agreement between local and global measurements of the London penetration depth
Recent measurements of the superconducting penetration depth in Ba(Fe1−xCox)2As2 appeared to disagree on the magnitude and curvature of Δλab(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.
This is a manuscript of an article published as Lippman, Thomas M., Beena Kalisky, Hyunsoo Kim, Makariy A. Tanatar, Sergey L. Bud’ko, Paul C. Canfield, Ruslan Prozorov, and Kathryn A. Moler. "Agreement between local and global measurements of the London penetration depth." Physica C: Superconductivity 483 (2012): 91-93. DOI: 10.1016/j.physc.2012.08.001. Posted with permission.