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Title: Critical fields and vortex pinning in overdoped Ba 0.2 K 0.8 Fe 2 As 2

We determine the upper and lower critical fields, the penetration depth and the vortex pinning characteristics of single crystals of overdoped Ba 0.2K 0.8Fe 2As 2 with T c ~ 10 K. We find that bulk vortex pinning is weak and vortex dynamics to be dominated by the geometrical surface barrier. The temperature dependence of the lower critical field, H c1, displays a distinctive upturn at low temperatures, which is suggestive of two distinct superconducting gaps. Furthermore, the penetration depth, λ, varies linearly with temperature below 4 K indicative of line nodes in the superconducting gap. As a result, these observations can be well described in a model based on a multi-band nodal superconducting gap.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Illinois, Chicago, IL (United States)
Publication Date:
OSTI Identifier:
1356359
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 17; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Materials Sciences and Engineering Division; Energy Frontier Research Center; Center for Emergent Superconductivity
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; phonons; thermal conductivity; energy storage (including batteries and capacitors); superconductivity; defects; spin dynamics