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Title: Critical fields and vortex pinning in overdoped Ba0.2K0.8Fe2As2

We determine the upper and lower critical fields, the penetration depth and the vortex pinning characteristics of single crystals of overdoped Ba0.2K0.8Fe2As2 with Tc ~ 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, Hc1, 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:
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
OSTI Identifier:
1356359
Alternate Identifier(s):
OSTI ID: 1182335