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Title: Pressure-induced phase coexistence in BaFe{sub 1.8}Co{sub 0.2}As{sub 2}

We report high-pressure powder synchrotron X-ray diffraction measurements of overdoped BaFe{sub 1.8}Co{sub 0.2}As{sub 2} under quasi-hydrostatic pressure up to 40.1 GPa. Our results indicate that a tetragonal (T) to collapsed tetragonal (CT) phase transition occurs at 16.8 GPa and the two phase coexist until 30 GPa, which has not been previously observed in iron arsenide compounds. Both the lattice parameters a and c show discontinuous change for the T and CT phases. The decrease of the c lattice parameter is as large as 12.2% owing to the uniaxial pressure effect. The axial ratio c/a of the T phase exhibits similar features to the other 122-type compounds below 16.8 GPa, whereas there is a very small increase with increasing pressure in the two phase coexistence region. Because of the relationship between the axial ratio and superconductivity, the abnormal expansion may be related to the sudden increase of the strength of antiferromagnetic spin fluctuations.
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Department of Physics, South China University of Technology, Guangzhou 510640 (China)
  2. (China)
  3. Department of Physics, Zhejiang University, Hangzhou 310027 (China)
  4. Center for High Pressure Science and Technology Advanced Research, Shanghai 201203 (China)
  5. (United States)
Publication Date:
OSTI Identifier:
22273607
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 14; 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; ANTIFERROMAGNETISM; BARIUM COMPOUNDS; COBALT ARSENIDES; FLUCTUATIONS; LATTICE PARAMETERS; PHASE TRANSFORMATIONS; POWDERS; PRESSURE DEPENDENCE; SPIN; SUPERCONDUCTIVITY; SUPERCONDUCTORS; TETRAGONAL LATTICES; X-RAY DIFFRACTION