caa a22 4500 445381396 CHVBK 20180317143018.0 cr unu---uuuuu 170323e20110101xx s 000 0 eng 10.1007/s10948-010-0944-0 doi (NATIONALLICENCE)springer-10.1007/s10948-010-0944-0 Polaron Dynamics and Coherent Acoustic Phonons inLa0.45Ca0.55MnO3 Thin Films Studied by Ultrafast Pump-Probe Spectroscopy [Elektronische Daten] [K. Wu, S. Lin, C. Luo, T. Uen, J.-Y. Lin, J. Juang] Pure phase, charge ordering (CO) (001)-oriented La0.45Ca0.55MnO3 thin films of thicknesses 250-600nm are prepared by pulsed laser deposition. The ultrafast dynamics in these films is probed by using the femtosecond optical pump-optical probe (OPOP) spectroscopy. The temporal evolution in transient reflectivity change ΔR/R has been systematically measured at various temperatures. Generally, the ΔR/R curve exhibits two relaxing components and two oscillating components. Similar to the case in La0.7Ca0.3MnO3 films, the amplitude of the fast relaxing component exhibits a similar temperature dependence with that of the resistivity, and the neutron scattering intensity due to nanoscale correlated polarons. Therefore, it corresponds to the polaron dynamics in the CO sample. Both oscillating components are ascribed to the coherent longitudinal acoustic phonons and are generated by the strain pulses. The origin of these oscillations is discussed and the sound velocity can be derived from the period of these oscillations. It is revealed that the sound velocity changed drastically near the CO transition temperature, which indicates that the pump-probe measurements can be employed as a sensitive probe to detect the CO phase transition in these samples. Springer Science+Business Media, LLC, 2010 Charge ordering nationallicence Perovskite manganites thin films nationallicence Polaron dynamics nationallicence Coherent acoustic phonon nationallicence Laser ultrasonics nationallicence Wu K. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C. aut Lin S. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C. aut Luo C. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C. aut Uen T. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C. aut Lin J.-Y Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C. aut Juang J. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C. aut Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/1-2(2011-01-01), 721-726 1557-1939 24:1-2<721 2011 24 10948 https://doi.org/10.1007/s10948-010-0944-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10948-010-0944-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wu K. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Lin S. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Luo C. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Uen T. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Lin J.-Y Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C aut NATIONALLICENCE 700 1- Juang J. Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, R.O.C aut NATIONALLICENCE 773 0- Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/1-2(2011-01-01), 721-726 1557-1939 24:1-2<721 2011 24 10948 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer