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Title: Unusually high critical current of clean P-doped BaFe{sub 2}As{sub 2} single crystalline thin film

Microstructurally clean, isovalently P-doped BaFe{sub 2}As{sub 2} (Ba-122) single crystalline thin films have been prepared on MgO (001) substrates by molecular beam epitaxy. These films show a superconducting transition temperature (T{sub c}) of over 30 K although P content is around 0.22, which is lower than the optimal one for single crystals (i.e., 0.33). The enhanced T{sub c} at this doping level is attributed to the in-plane tensile strain. The strained film shows high transport self-field critical current densities (J{sub c}) of over 6 MA/cm{sup 2} at 4.2 K, which are among the highest for Fe based superconductors (FeSCs). In-field J{sub c} exceeds 0.1 MA/cm{sup 2} at μ{sub 0}H=35 T for H‖ab and μ{sub 0}H=18 T for H‖c at 4.2 K, respectively, in spite of moderate upper critical fields compared to other FeSCs with similar T{sub c}. Structural investigations reveal no defects or misoriented grains pointing to strong pinning centers. We relate this unexpected high J{sub c} to a strong enhancement of the vortex core energy at optimal T{sub c}, driven by in-plane strain and doping. These unusually high J{sub c} make P-doped Ba-122 very favorable for high-field magnet applications.
Authors:
; ;  [1] ;  [2] ; ;  [3] ; ; ;  [1] ;  [1] ;  [2] ; ; ; ;  [4] ;  [5] ;  [1] ;  [6]
  1. Institute for Metallic Materials, IFW Dresden, 01171 Dresden (Germany)
  2. (Germany)
  3. Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, 2031 East Paul Dirac Drive, Tallahassee, Florida 32310 (United States)
  4. Department of Crystalline Materials Science, Nagoya University, Chikusa, Nagoya 464-8603 (Japan)
  5. Karlsruhe Institute of Technology, Institute for Technical Physics, Hermann von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
  6. (Japan)
Publication Date:
OSTI Identifier:
22412661
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 7; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BARIUM COMPOUNDS; COMPARATIVE EVALUATIONS; CRITICAL CURRENT; CRITICAL FIELD; CURRENT DENSITY; DOPED MATERIALS; IRON ARSENIDES; MAGNESIUM OXIDES; MAGNETS; MICROSTRUCTURE; MOLECULAR BEAM EPITAXY; MONOCRYSTALS; STRAINS; SUBSTRATES; SUPERCONDUCTORS; THIN FILMS; TRANSITION TEMPERATURE; VORTICES