Phase Change Observed in Ultrathin Ba0.5Sr0.5TiO3 Films by in-situ Resonant Photoemission Spectroscopy

Authors :: Lin, Y. -H.
Terai, K.
Wadati, H.
Kobayashi, M.
Takizawa, M.
Hwang, J. I.
Fujimori, A.
Nan, C. -W.
Li, J. -F.
Fujimori, S. -I.
Okane, T.
Saitoh, Y.
Kobayashi, K.
Source :: Appl. Phys. Lett. 90, 222909 (2007)
Publication Year :: 2007
Abstract: Epitaxial Ba0.5Sr0.5TiO3 thin films were prepared on Nb-doped SrTiO3 (100)substrates by the pulsed laser deposition technique, and were studied by measuring the Ti 2p - 3d resonant photoemission spectra in the valence-band region as a function of film thickness, both at room temperature and low temperature. Our results demonstrated an abrupt variation in the spectral structures between 2.8 nm (~7 monolayers) and 2.0 nm (~5 monolayers) Ba0.5Sr0.5TiO3 films, suggesting that there exists a critical thickness for phase change in the range of 2.0 nm to 2.8 nm. This may be ascribed mainly to the intrinsic size effects.<br />Comment: 13 pages, 4 figures

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