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Unconventional London Penetration Depth in Single-Crystal Ba(Fe0.93Co0.07)(2)As-2 Superconductors

TitleUnconventional London Penetration Depth in Single-Crystal Ba(Fe0.93Co0.07)(2)As-2 Superconductors
Publication TypeJournal Article
Year of Publication2009
AuthorsGordon RT, Ni N, Martin C, Tanatar MA, Vannette MD, Kim H, Samolyuk GD, Schmalian J, Nandi S, Kreyssig A, Goldman AI, Yan JQ, Bud'ko SL, Canfield PC, Prozorov R
Journal TitlePhysical Review Letters
Volume102
Pages127004
Date Published03/27
ISBN Number0031-9007
Accession NumberISI:000264632100059
Keywordsgap, layered superconductor, magnetic-field
Abstract

The London penetration depth lambda(T) has been measured in single crystals of Ba(Fe0.93Co0.07)(2)As-2. The observed low-temperature variation of lambda(T) follows a power law, Delta lambda(T)similar to T-n with n approximate to 2.4 +/- 0.1, indicating the existence of normal quasiparticles down to at least 0.02T(c). This is in contrast with previous penetration depth measurements on single crystals of NdFeAsO1-xFx and SmFeAsO1-xFx, which indicate an anisotropic but nodeless gap. We discuss possible explanations of the observed power law behavior.
URL<Go to ISI>://000264632100059
DOI10.1103/Physrevlett.102.127004