Pressure effects on the charge ordering in Bi0.4Ca0.6MnO3 films of different orientationJ. Z. Wang1, J. R. Sun1, W. Zhang1, R. C. Yu1, Y. Z. Chen1, B. G. Shen1 and W. B. Wu2
1 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences - Beijing 100080, PRC
2 Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China - Hefei 230026, PRC
received 22 November 2007; accepted in final form 5 February 2008; published April 2008
published online 18 March 2008
Effects of hydrostatic pressure on the charge ordering (CO) transition in the Bi0.4Ca0.6MnO3 films respectively grown on (110) and (111) SrTiO3 substrates have been experimentally studied. X-ray diffraction analysis indicates the occurrence of very differently deformed structures of the two films. Linear decrease of the CO temperature (TCO)at different rates, ~ 12K/GPa for the (110)-film and ~ 19K/GPa for the (111)-film, is observed. Accompanying the depression of TCO, partial melting of the charge-ordered phase occurs above a threshold pressure, ~ 0.8/1.2 GPa for the (111)/(110)-film. Analysis of the relative volume fraction of the CO phase, obtained based on the effective medium theory, shows that the CO collapsing occurs in a wide pressure range, typically ~ 1.2 GPa in width, and there will be no long-range CO phase above the pressure of ~ 2/2.3 GPa for the (111)/(110)-film. There is an exact correspondence between the CO melting and the pressure-driven upturn of resistivity above TCO, suggesting the simultaneous occurrence of CO melting and shear-type lattice distortion. Different lattice strains are believed to be the reason for the dissimilar behaviors of the two films.
61.50.Ks - Crystallographic aspects of phase transformations; pressure effects.
75.47.Lx - Manganites.
73.50.-h - Electronic transport phenomena in thin films.
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