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Title: Conventional empirical law reverses in the phase transitions of 122-type iron-based superconductors

Phase transition of solid-state materials is a fundamental research topic in condensed matter physics, materials science and geophysics. It has been well accepted and widely proven that isostructural compounds containing different cations undergo same pressure-induced phase transitions but at progressively lower pressures as the cation radii increases. However, we discovered that this conventional law reverses in the structural transitions in 122-type iron-based superconductors. In this report, a combined low temperature and high pressure X-ray diffraction (XRD) measurement has identified the phase transition curves among the tetragonal (T), orthorhombic (O) and the collapsed-tetragonal (cT) phases in the structural phase diagram of the iron-based superconductor AFe2As2 (A = Ca, Sr, Eu, and Ba). As a result, the cation radii dependence of the phase transition pressure (T → cT) shows an opposite trend in which the compounds with larger ambient radii cations have a higher transition pressure.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [1] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11]
  1. Center for High Pressure Science and Technology Advanced Research, Shanghai (China)
  2. Center for High Pressure Science and Technology Advanced Research, Shanghai (China); Jilin Univ., Changchun (China); Carnegie Institute of Washington, Argonne, IL (United States)
  3. Harbin Institute of Technology, Harbin (China)
  4. Center for High Pressure Science and Technology Advanced Research, Shanghai (China); Harbin Institute of Technology, Harbin (China)
  5. Carnegie Institute of Washington, Argonne, IL (United States)
  6. Chinese Academy of Sciences (CAS), Beijing (China)
  7. Chinese Academy of Sciences (CAS), Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
  8. Collaborative Innovation Center of Quantum Matter, Beijing (China); Peking Univ., Beijing (China)
  9. Chinese Academy of Sciences (CAS), Shanghai (China)
  10. Univ. of Nevada, Las Vegas, NV (United States)
  11. Center for High Pressure Science and Technology Advanced Research, Shanghai (China); Carnegie Institute of Washington, Argonne, IL (United States)
Publication Date:
OSTI Identifier:
1164958
Grant/Contract Number:
AC02-06CH11357; SC0001057
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 4; Journal Issue: 11, 2014; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY phase transitions and critical phenomena; structure of solids and liquids