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Title: Giant increase of critical current density and vortex pinning in Mn doped K{sub x}Fe{sub 2−y}Se{sub 2} single crystals

We report a comparative study of the critical current density (J{sub c}) and vortex pinning among pure and Mn doped K{sub x}Fe{sub 2−y}Se{sub 2} single crystals. It is found that the J{sub c} values can be greatly improved by Mn doping and post-quenching treatment when comparing to pristine pure sample. In contrast to pure samples, an anomalous second magnetization peak (SMP) effect is observed in both 1% and 2% Mn doped samples at T = 3 K for H∥ab but not for H∥c. Referring to Dew-Hughes and Kramer's model, we performed scaling analyses of the vortex pinning force density vs magnetic field in 1% Mn doped and quenched pristine crystals. The results show that the normal point defects are the dominant pinning sources, which probably originate from the variations of intercalated K atoms. We propose that the large nonsuperconducting K-Mn-Se inclusions may contribute to the partial normal surface pinning and give rise to the anomalous SMP effect for H∥ab in Mn doped crystals. These results may facilitate further understanding of the superconductivity and vortex pinning in intercalated iron-selenides superconductors.
Authors:
;  [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. Department of Physics, Shanghai University, Shanghai 200444 (China)
  2. (China)
  3. College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China)
  4. INPAC-Institute for Nanoscale Physics and Chemistry, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22391960
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 19; Other Information: (c) 2014 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; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CLATHRATES; CRITICAL CURRENT; CURRENT DENSITY; DOPED MATERIALS; IRON SELENIDES; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIZATION; MANGANESE; MONOCRYSTALS; POINT DEFECTS; POTASSIUM; QUENCHING; SELENIUM; SUPERCONDUCTIVITY; SUPERCONDUCTORS; TEMPERATURE RANGE 0000-0013 K; VORTICES