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Title: Structural instability of the CoO4 tetrahedral chain in SrCoO3-δ thin films

Raman scattering experiments together with detailed lattice dynamic calculations are performed to elucidate crystallographic and electronic peculiarities of SrCoO3-δ films. We observe that the 85 cm-1 phonon mode involving the rotation of a CoO4 tetrahedron undergoes a hardening by 21 cm-1 when the temperature is decreased. In addition, new phonon modes appear at 651.5 and 697.6 cm-1 . The latter modes are attributed to the Jahn-Teller activated modes. Upon cooling from room temperature, all phonons exhibit an exponential-like increase of intensity with a characteristic energy of about 103–107 K. We attribute this phenomenon to an instability of the CoO4 tetrahedral chain structure, which constitutes a key ingredient to understand the electronic and structural properties of the brownmillerite SrCoO2.5.
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5]
  1. Chung-Ang Univ., Seoul (South Korea)
  2. Braunschwig Univ. of Technology (Germany)
  3. SungKyunKwan Univ., Suwon (Korea)
  4. Pusan National Univ., Busan (Korea)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 118; Journal Issue: 8; Journal ID: ISSN 0021-8979
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States