London penetration depth in iron-based superconductors

TitleLondon penetration depth in iron-based superconductors
Publication TypeJournal Article
Year of Publication2011
AuthorsProzorov R, Kogan VG
Journal TitleReports on Progress in Physics
Volume74
Pages124505
Date Published12
Type of ArticleReview
ISBN Number0034-4885
Accession NumberWOS:000298079500006
Keywordsanisotropic, ba0.6k0.4fe2as2, function, gap, high-temperature superconductivity, impurities, layered superconductor, single-crystals, state, superconductors, superfluid density, thermodynamics
Abstract

Measurements of London penetration depth, a sensitive tool to study multiband superconductivity, have provided several important insights into the behavior of Fe-based superconductors. We first briefly review the 'experimentalist-friendly' self-consistent Eilenberger two-band model that relates the measurable superfluid density and temperature dependences of the superconducting gaps. Then we focus on BaFe(2)As(2)-derived materials, for which the results are consistent with (1) two distinct superconducting gaps; (2) development of strong in-plane gap anisotropy with departure from optimal doping; (3) development of gap nodes along the c direction in a highly overdoped regime; (4) significant pair-breaking, presumably due to charge doping; (5) fully gapped intrinsic behavior (exponential at low temperatures) at optimal doping if the scattering is removed (probed in the 'self-doped' stoichiometric LiFeAs); (6) competition between the magnetically ordered state and superconductivity, which do coexist in underdoped compounds. Overall, it appears that while there are common trends in the behavior of Fe-based superconductors, the gap structure is non-universal and is quite sensitive to the doping level. It is plausible that the rich variety of possible gap structures within the general s(+/-) framework is responsible for the observed behavior.

URL<Go to ISI>://WOS:000298079500006
DOI10.1088/0034-4885/74/12/124505
Alternate JournalRep. Prog. Phys.