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Title: Structural instability of the CoO{sub 4} tetrahedral chain in SrCoO{sub 3−δ} thin films

Raman scattering experiments together with detailed lattice dynamic calculations are performed to elucidate crystallographic and electronic peculiarities of SrCoO{sub 3−δ} films. We observe that the 85 cm{sup −1} phonon mode involving the rotation of a CoO{sub 4} tetrahedron undergoes a huge hardening by 21 cm{sup −1} with decreasing temperature. In addition, new phonon modes appear at 651.5 and 697.6 cm{sup −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 CoO{sub 4} tetrahedral chain structure, which constitutes a key ingredient to understand the electronic and structural properties of the brownmillerite SrCoO{sub 2.5}.
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ; ;  [5]
  1. Department of Physics, Chung-Ang University, Seoul 156-756 (Korea, Republic of)
  2. Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany and Laboratory for Emerging Nanometrology, TU Braunschweig, Braunschweig (Germany)
  3. Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)
  4. Department of Physics, Pusan National University, Busan 609-735 (Korea, Republic of)
  5. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Publication Date:
OSTI Identifier:
22494810
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 8; Other Information: (c) 2015 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; COBALT OXIDES; COOLING; CRYSTALLOGRAPHY; HARDENING; JAHN-TELLER EFFECT; PHONONS; RAMAN EFFECT; ROTATION; TEMPERATURE RANGE 0273-0400 K; THIN FILMS