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Title: Abnormal thermal expansion, multiple transitions, magnetocaloric effect, and electronic structure of Gd{sub 6}Co{sub 4.85}

The structure of known Gd{sub 4}Co{sub 3} compound is re-determined as Gd{sub 6}Co{sub 4.85}, adopting the Gd{sub 6}Co{sub 1.67}Si{sub 3} structure type, which is characterized by two disorder Co sites filling the Gd octahedral and a short Gd-Gd distance within the octahedra. The compound shows uniaxial negative thermal expansion in paramagnetic state, significant negative expansion in ferromagnetic state, and positive expansion below ca. 140 K. It also exhibits large magnetocaloric effect, with an entropy change of −6.4 J kg{sup −1} K{sup −1} at 50 kOe. In the lattice of the compound, Co atoms at different sites show different spin states. It was confirmed by the X-ray photoelectron spectra and calculation of electronic structure and shed lights on the abnormal thermal expansion. The stability of such compound and the origin of its magnetism are also discussed based on measured and calculated electronic structures.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [5] ;  [1]
  1. Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong (Hong Kong)
  2. (United States)
  3. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)
  4. (China)
  5. Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 (United States)
Publication Date:
OSTI Identifier:
22492769
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 13; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMS; DISTANCE; ELECTRONIC STRUCTURE; ENTROPY; MAGNETIC PROPERTIES; PARAMAGNETISM; SPIN; THERMAL EXPANSION; X-RAY PHOTOELECTRON SPECTROSCOPY