摘要
We report on a systematic study of the thickness dependence of the optical properties of La0.7 Sr0.3 Mn O3 thin films epitaxially grown on a LaAl O3 substrate. The x-ray powder-diffraction data indicate that the c -axis lattice constant is enhanced with decreasing the film thickness due to the compressive strain in the film plane produced by lattice mismatch. Magnetization curves show a decrease of the Curie temperature (TC) for decreasing thickness of films. Optical reflectance and transmittance measurements provide evidence that the position of Mn-O stretching mode shifts toward low frequency and the energy of the charge-transfer transition between O 2p and Mn 3d states increases with the decrease of film thickness. Most importantly, an analysis of the small-polaron absorption in the mid-infrared region shows that the polaron binding energy increases with decreasing the film thickness, suggesting that the strain dependence of TC mainly results from the strain-induced electron-phonon coupling.
原文 | ???core.languages.en_GB??? |
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文章編號 | 113528 |
期刊 | Journal of Applied Physics |
卷 | 97 |
發行號 | 11 |
DOIs | |
出版狀態 | 已出版 - 2005 |