Epitaxially strained Na0.7CoO2 thin films on SrTiO3 buffer layer

J. Y. Son, Y. H. Shin, Hyungjun Kim

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1 Citation (Scopus)


We prepared Na0.7CoO2 thin films on (0 0 1) Al2O3 substrates that showed a negligibly strained structure and a metallic behavior similar to Na0.7CoO2 single crystal. In particular, a Na0.7CoO2 thin film on a (1 1 1) SrTiO3/(0 0 1) Al2O3 substrate exhibited an elongated c-lattice constant as well as an anomaly in the electric transporting behavior: a transition from an insulating state to a metallic state at 105 K. This change is caused by the structural symmetry break near the cubic-to-tetragonal transition temperature of SrTiO3. From spectroscopic ellipsometry analysis, we obtained optical conductivities for the Na0.7CoO2 thin films on the Al2O3 and SrTiO3/Al2O3 substrates. The Na0.7CoO2 thin film on the SrTiO3/Al2O3 substrate exhibited higher energy splitting between eg and a1g than the Na0.7CoO2 thin film on the Al2O3 substrate, resulting from the c-lattice elongation.

Original languageEnglish
Pages (from-to)1021-1024
Number of pages4
JournalJournal of Crystal Growth
Issue number4
Publication statusPublished - 2009 Feb 1

Bibliographical note

Funding Information:
This work was supported by the Brain Korea 21 Project 2006.

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry


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